~ offtopic ~
No one said prefixes aren't rare, but seems the ignorance is on your side, because:
- no one is gonna waste a ton of power to find the exceptional case where two sequential keys result in a very long common prefix; that's a waste of time. Having infinitely small chances of a collision is the main reason why you don't see two near keys colliding, not because you've just found some prefix and that would somehow mean it has any sort of relevance for the very next hash, be it the next one or 500 billion keys later.
I believe you are correct. We know 10k gpu's can find one of these keys. But that's for other people, not me, for sure. This also isn't, in my opinion, testing the strength of ecdsa or bitcoin. I look at this from a technicality perspective; is there a weakness in math, random, or a code exploit. For a long time I've chatted with the GPT's and there is consensus that ecdsa and elliptic curve algorithms are elegant and no vulnerabilities are expected. The only error is human in poor entropy or coding. I've pressed Ctrl + c so many times. But I enjoy the "think tank" collaboration in this thread.