Summary: Risks of Mining Pool Centralization | Jimmy Song, TFTC Podcast (Center of Hash E008)

Podcast Details

• Podcast: TFTC: A Bitcoin Podcast
• Host: Marty Bent
• Guest: Jimmy Song (Bitcoin educator, developer)
• Date: September 16, 2025
• Main Theme: Exploring the risks of Bitcoin mining pool centralization, the distinction between hashing and mining, consensus vs. relay policy, and decentralization’s effect on the network’s resilience.

Episode Overview

Marty Bent and Jimmy Song engage in a comprehensive discussion focused on the centralization of mining pools within the Bitcoin network. They analyze the risks associated with a small number of entities controlling block construction, lay out the complexities around consensus rules and relay policy, and reflect on the evolution and consequences of these trends for Bitcoin’s security and political neutrality. The tone oscillates between technical deep dives and philosophical concern for Bitcoin's long-term decentralization.

Key Discussion Points and Insights

1. Hashers, Miners, and Pools: Defining the Terms

• Hashers are those who own and run ASICs, consuming electricity to perform Proof of Work.

• Mining Pools group hashers’ computational power for variance reduction, distributing rewards according to contributions.

• Pool Operators have outsized power as they construct the block templates and distribute payouts to individual hashers.

• Centralization Concern: As few as 6–7 pools command about 90% of global hash rate, raising the specter of cartel-like behavior and increased attack surface (05:37, 12:22).

  "We shouldn't call these people that are participating in a pool not really running their own nodes or constructing blocks like an actual miner. They're not really mining as much as they are hashing. The mining pools are mining because they're constructing their own blocks."
  — Jimmy Song (06:30)

2. Block Construction & Centralization

• Pool operators decide which transactions are included in blocks. Most hashers don’t run their own nodes; they trust pools for payouts and block decisions.

• Historical context: Nearly all hash rate operates under centralized pools using older protocols (Stratum v1), with few exceptions (CK Solo, Ocean, Brains with Stratum v2).

• This makes it easy for external forces (industry cartels, governments) to pressure pool operators, threatening Bitcoin’s censorship resistance (04:13, 20:01).

  “When a centralized entity exists, then you can sort of choke it and bend it to your will, which is the scenario you’re more broadly describing.”
  — Jimmy Song (20:01)

3. Principal Risks of Pool Centralization

• Cartel Power: Pools could coordinate to enforce minimum transaction fees, exclude certain transaction types, or engage in blanket censorship (e.g., OFAC sanctioned addresses) (12:22–14:15).

• Regulatory Choke Points: Fewer, larger entities are easier for regulators to target, increasing the risk of political or economic coercion.

• Hard vs. Soft Forks: A concentrated set of mining entities could more easily force chain splits, either for changing the 21M supply cap or censoring addresses (14:33, 17:34).

• Relay Policy Risks: If consensus around mempool relay policy is lost, centralization can allow rapid, ill-considered shifts that don’t reflect broader user consensus (46:05).

  “If you have block construction outsourced to only a few entities, then they can do cartel-like behavior.”
  — Jimmy Song (12:26)

4. Consensus Rules vs. Relay Policy

• Consensus Rules are the hard-coded, protocol-level rules all nodes enforce (21 million cap, block limits, opcode behavior). Only these rules define true Bitcoin.

  • Hard fork: Loosening the rules (e.g., bigger block size), causing chain splits.
  • Soft fork: Tightening rules; can cause wipeouts if not broadly adopted (25:11, 30:36).

• Relay Policy: Mempool and transaction relay are node-level behaviors. They can limit what’s gossiped/shared even if technically valid. Relay policy is often more conservative to prevent resource exhaustion (e.g., OP_RETURN size, malformed transactions).

• Risks arise if a handful of pools run new relay rules, altering mempool incentives and fee markets without broad agreement—setting precedents for more contentious changes (33:04, 38:31).

  “It should be difficult to change the relay policy... It should be even harder to change consensus rules, which it is. Centralization creates a scenario where changing the relay policy could mean only six or seven mining pools get to decide.”
  — Marty Bent (46:05)

5. Game Theory: Forks, Futures, and Miner Alignment

• When pools adopt contentious rules, minority users/miners risk getting wiped out (block reorgs) unless they can coordinate their own fork (68:33–73:58).

• Futures markets (as seen in the 2017 block size debate) could emerge to price in which chain will have true economic majority.

• Miners are generally responsive to perceived economic risks; as in 2017, fears of orphaned blocks or economic irrelevance make pools quick to abandon contentious changes.

• The current low engagement of most individual miners (who hash for pools) weakens checks on centralized pool decisions (81:12).

  “The bigger risk, I think comes from the developers where if they get to set this relay policy against the wishes of... users, then can they do that with a soft work, a contentious one?”
  — Jimmy Song (47:33)

6. Developer Power, User Voice, and Precedent

• Concerns are raised that a tight developer consensus, coupled with mining pool agreement, could push changes (even those with broad user dissent) by inertia—especially for relay policy, but also (in theory) for consensus changes (55:31–65:57).

• The current OP_RETURN relay debate is cited as an example of diminished openness to genuine community critique.

• Developers may say “run your own version,” but ecosystem inertia and absence of alternatives leads to de facto central planning (57:20).

  "One of the things about a lot of coders is that they’re not entirely socially aware and they think they’re hiding their motivations... They think they're in the right and they think they know better than everybody else and they are basically making it so that it's going in whether you like it or not."
  — Jimmy Song (57:56)

7. Miners’ Detachment and Fiat Incentives

• Most hashers remain disengaged from governance and policy changes. Economic incentives provided by fiat funding mechanisms (cheap loans, stock issuance) promote size and inertia instead of profit-focused participation.

• Centralization is further exacerbated by large-scale players whose bottom lines depend more on fiat capital markets than mining revenue (80:05).

• More home and small-business mining, plus the overall collapse of fiat incentives, are forecast as potential cures—though distant for now (83:42).

  "If these cashers were more focused on profit, then I think all the problems solve themselves. Market forces would force them into a more decentralized and active participation... Once the fiat system collapses, mining will be fixing itself."
  — Jimmy Song (83:42)

8. Decentralization: Hope for the Future

• Innovations like home heating, modular power, and using excess home energy may drive more distributed mining in the longer term, solving many problems at their root.

• Until then, the centralization of both energy production and mining due to fiat incentives remains a critical challenge for Bitcoin’s resistance to change from within.

  “I think there’s a lot of potential... as more innovations come in... The reality is today the level of centralization... makes it easier to change bitcoin when it otherwise should be harder.”
  — Marty Bent (86:46, 88:35)

Notable Quotes & Timestamps

• Mining Pools as Central Points of Failure:
  "There are only maybe 15 pools that have something like 95% of the hash rate... 95% of hash rate essentially is controlled by like 16 pool operators. And... probably more like 10 at the most."
  — Jimmy Song (04:13)

• Cartel Threats:
  "They could just say, hey, if you want a transaction, you have to pay US$500 per transaction. We're not going to include anything else. That could be cartel like behavior."
  — Jimmy Song (12:26)

• Relay Policy vs. Consensus:
  "It's a lot like the distinction between legality and morality sometimes where something is technically legal, but it's morally dubious. As a node, sometimes you want to just filter for those things..."
  — Jimmy Song (36:19)

• Developer Power Dynamics:
  “What I am concerned about is the process... Even though there's a whole bunch of people in the community that don't like this change, we're going to go ahead with it anyway.”
  — Jimmy Song (55:31)

• On Miners' Disengagement:
  "They're sort of mercenaries, right? Like hash rate for sale. And yeah, it's unfortunate because it would be better if they were all sort of individually making decisions and cared about the network... It's a little bit of a fiat artifact."
  — Jimmy Song (76:16)

Important Segment Timestamps

• Introduction & Brisket Inflation Context: (00:04–02:33)
• Pool Mining, Stratum, and Hash Rate Control: (02:55–07:40)
• Security Properties of PoW, Finality Discussion: (07:49–10:52)
• Mining Pool Market Share & Concentration: (10:52–12:22)
• Risks: Cartels, Censorship, and Soft Fork Dynamics: (12:22–19:13)
• Consensus vs. Relay Policy, Hard/Soft Forks: (25:11–38:31)
• Relay Policy & Mempool Node Behavior: (38:31–46:05)
• Precedent & Game Theory of Developer/Pool Changes: (47:33–73:58)
• Fiat Incentives and Mining Centralization: (80:05–83:42)
• Innovation and the Path Towards Re-Decentralization: (85:38–88:35)
• Outro: (89:11–end)

Takeaways

• Critical Risks: Mining pool centralization is a significant vector for external pressure, censorship, and network capture.
• Relay Policy Precedent: Handing de facto policy control to a few pools or developers threatens Bitcoin's apolitical, decentralized tradition.
• Economic Realities: As long as fiat incentives dominate mining, decentralization faces headwinds.
• Hope for Users: Encouraging more diverse, profit-driven, and grassroots participation—at the miner and developer levels—is essential for Bitcoin’s future robustness.

This summary reflects the rich, technical, and sometimes concerned tone of the episode, highlighting the importance of vigilance and engagement from all network participants to ensure Bitcoin’s ongoing resistance to change-by-fiat and centralization.