it's legit, but probably further in the future. supercomputers already are a threat, if there is a big enough UTXO to sell after cracking its key. plenty of yuge UTXOs especially in the first year of the chain, ones that probably are lost keys. quantum computers DO work, at a much lower (about 50%) power cost compared to equivalent conventional computers. i would suspect that memory technology like Google's TPU systolic array memory will probably prove to be helpful in accelerating this kind of processing as well, though not as much as it helps LLM models, as it could be modified to implement a possible shortcut in the pubkey derivation by using humongous precalculated tables. and funny, isn't it, how the bitcoin devs decided to make taproot reveal the pubkey in the spend, so the receiver is then vulnerable to a bruteforce attack. bruteforcing hashes is harder than bruteforcing pubkey/secret key reversal.