I think there's a lot of sunk cost in those comments, along with a lot of frustrated ideology. For people who thought they had finally gotten a way to bring their ideology into the real world, or imagined all sorts of riches, the state of crypto and the burgeoning regulatory environment may be too much to emotionally process and accept.
As for why there isn't much in the way of thorough rebuttals, I suspect anyone trying to formulate one would pretty rapidly run into the wall of reality not agreeing with their existing stance.
Maybe the truly ideological (an-cap types), sure, but many of the “most ideological” are just religiously greedy and want the best of all worlds — basic logic be damned.
Regulated exchanges and coins in cold storage you can’t do much with is the worst of both worlds for those people.
The “not your keys set” is fine, most of them got their BTC at $1 and if BTC falls to $3 they still tripled initial investment.
The people who got in later don’t understand “owning” a bitcoin on an exchange and having the key in your possession are VERY different. Those people are idiots.
As for why there isn't much in the way of thorough rebuttals, I suspect anyone trying to formulate one would pretty rapidly run into the wall of reality not agreeing with their existing stance.