Hybrid Mining Fallacy

There is a theory that a combination of proof-of-work (PoW) and proof-of-stake (PoS) mining offers a higher level of system security than PoW. The theory implies that a majority of coin owners can mitigate "misbehavior" by PoW miners.

In the absence of a majority hash power miner, there is nothing to mitigate. Therefore the theory is premised on increasing the cost of a censorship regime. This rests on the unsupportable assumption that PoW miners are not also PoS miners.

The cost of hybrid mining is the combined costs of work and staking, inclusive of capital cost. The return on mining investment necessarily equates to capital cost, as a consequence of competition. As mining is profitable, capital cost does not contribute to security. Achieving majority stake is no more costly than achieving majority hash power. The theory is therefore invalid.

Given a model whereby a majority stakeholder can prevent confirmation of otherwise valid PoW blocks, once a majority is achieved the censor cannot be unseated. Such a system is fundamentally a PoS coin, lacking censorship resistance, with the PoW aspect providing no additional security.