It's highly unlikely that anyone could crack your Bitcoin wallet's seed phrase, even if they had access to a supercomputer. Your seed phrase is like a super-secret password, but it's incredibly long and random. Think of it this way: a typical seed phrase contains 12 or 24 words chosen from a list of over 2000 words, this means there are 2048^12 or 2048^24 possible combinations. That's a mindboggling number of possible combinations, even the most powerful supercomputers would take an absurdly long time to try every combination. However, never share your phrase with anyone, once they have it, no need for any bruteforce attempt.
as you said it is impossible.. Even if it were possible, Bitcoin would have been damaged and abandoned a long time ago because of this. The only way someone can open a wallet is by having or knowing the wallet's seed phrase or private key. Even to crack one phrase or private key by a supercomputer it may take several years or even not at all, and this is not worth the time spent.