What Are the Risks of a Mining Pool Operator Having Malicious Intent?

A malicious pool operator can launch a 51% attack if the pool controls enough hash rate, allowing them to double-spend or censor transactions. They could also engage in 'block withholding,' where they find a block but do not broadcast it, causing the pool's miners to waste effort and the network to slow down.

Furthermore, they could misreport pool statistics or mismanage the distribution of rewards.