What Is the Theoretical Upper Bound for the Selfish Mining Profitability Threshold?

The theoretical upper bound for the hashrate required for selfish mining to be profitable is often cited as 33.3%, or one-third of the total network hashrate. At this point, the selfish miner can always guarantee that their chain will win against the honest network's chain in the long run, even under ideal network conditions with zero latency.

If the hashrate exceeds 33.3%, the advantage becomes more pronounced, but the 25% to 33.3% range is the critical zone.