- "A pool with >50% wouldn't attack because they would destroy their own business model" doesn't really matter: What matters is how many people someone interested in *destroying bitcoin* would have to coerce.
That number is currently 2.Seriously. We should probably be nervous whenever there are pool ops controlling more than 10% each. Which thus far has been all the time. We should also be looking further out to when most mining is done for heat generation and plan ways to ensure that this mining is not controlled by a single entity while still being monitored actively enough to respond to incidents like the hard fork a while back.
