Reverse buyer's remorse.

They've known about it long enough to have profited in fiat terms from Bitcoin.

This bruises their ego because they've objectively been wrong during that time, and they know it.

They can't handle the idea that they've been wrong...UNLESS they were only wrong for a little while until ULTIMATELY being proven RIGHT in the end.

It's the sunken cost fallacy which is the bread and butter of the ego.