If I had a quantum computer and was working in intelligence the first thing I'd set it upon is breaking SHA-256.
What makes you think that when quantum computing technology works (everything that exists now is just prototypes) SHA-256 will not have adequate protection against quantum attacks? Technology travels in different directions, attack <---> defense, but for that there is still a lot of research needed and it takes a long time.
i agree that all crypto should move to quantum resistant technology, u should remember that insurance companies were created only to protect you from risks that rarely happen to you, with a 99% chance they won't
if you own a large amount of cryptocurrency on major blockchains, is it a good idea to take the risk of waiting to see if quantum computers (or computer power) can break the SHA256 algorithm of Bitcoin or the algorithms of existing altcoins?
maybe a few people will like it, but i'm sure your wife, children, and even your mistress won't like it. because that's what really matters, right?
one thing to note is that you never know when the 23 years SHA256 technology will be cracked if quantum computers (computer power) are combined with AI, ML, biology tech ... in the coming years. big players like Apple's iMessage have already moved to quantum resistance, and Google/IBM have set a goal of 1 million qubits, and more.... it's naive to think that Bitcoin will never have the ability to be cracked in the age of AI and quantum computing