Fraudulent blocks have to be sustained, that is the fraudster has to keep adding to its fraudulent chain to avoid getting spotted and busted. PoW makes this nearly impossible (unless you have so much hash power that you keep winning the lottery. In 2023? ).

Digging far back, we can find instances of chain being rolled back or patched due to error and/or attacks. But we talking 2013.

Hackers who tried to crack the network for fun and challenge came to this conclusion: Satoshi cannot be a single person. Every bug they wrote (beautiful bugs) not only wouldn’t work but would be greeted by a “well tried” message from satoshi.