Even Bitcoin core developers, which should be well above average in understanding crypto and good opsec, have had their Bitcoin stolen.

The issue in not trying to force one solution for everyone becomes a blocker when you intend on making some technology useful and essential to everyone, hence, no one seriously gives a damn about crypto anymore.

The claim that most humans are prone to losing keys isn't negated by the existence of some humans that have (so far) been able to keep their keys.