What Percentage of Hashrate Is Required for Selfish Mining to Be Profitable?

Selfish mining becomes theoretically profitable when a miner controls slightly more than one-third (33.3%) of the network's total hashrate. Below this threshold, the selfish strategy generally yields less revenue than honest mining due to the risk of the network finding the next block before the selfish miner can publish their longer chain.

The original research paper suggested a threshold around 25%, but subsequent analysis refined this, showing profitability requires greater than 33.3% to consistently outperform honest mining. This attack relies on withholding newly found blocks to gain a temporary lead.