who decides whether a quantum threat is “imminent?”
why should anyone trust an “altruistic” actor to destroy someone’s property rights before a quantum computer does?
how do you know coins...
You are 100% correct. Brute force guessing of private keys has always been and will always be a possibility. Once we allow this to be justification for stealing (aka freezing) coins, Bitcoin will cease to provide any assurance of property ownership. Your coins will only be secure as long as the anointed high priests of Bitcoin core say so.
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