People can guess private keys? Seriously? No one is capable of doing that genius. Many have tried to crack these keys in different ways(Brute force etc), but failed which is why a large portion of BTC is lost basically.
Supercomputers could possibly crack them in the future, but it would still be really difficult.
If you are guessing, there's nothing genius in it.
Agree on this, I think even a genius person could not even crack even one of million private keys exixting. Using a super computer to crack private key combination might not be possible, or could be possibe but might take ages.
Cracking a particular account private key can be very difficult. However, as Bitcoin accounts continue to grow at a large scale. At some point in the future, any combination of 256 numbers and letters may be a private key. People can guess the private key of an account.