What prevents hackers from guessing seed phrases?
The problem for the guesser is that 204812 is a very big number (204824 more so).
It is roughly 5,000,000,000,000,000,000,000,000,000,000,000,000,000
Let's say a hundred million different people have Bitcoin wallets and have money.
Lets say a million attackers each guess a million phrases a second.