I doubt most investors are regretting now or at least I hope so.

Just from the fact that most of us probably weren't around that time and a lot of us only invested in bitcoin when it was gaining value already. It is easy to be disappointed during the early years because obviously no one knew that it would bounce back. But if someone from recent times sold before bitcoin even hit $100k, he should definitely regret his actions lol. Not yet too late to correct it though.