I have attempted to move to Firefox twice: once 12 years ago and once 8 years ago (probably, I don't really remember exact time). I know, Firefox has come a long, long, long way since then, but the same were also promised 8 years ago, and it turn out Firefox cannot handle my use case well to the point of almost being unusable. (That said, my use case are definitely not normal)

It's a lot of effort to move everything: current session, bookmarks, extensions, sync (which mean I need to move on my 5+ devices at once). I have been bitten twice -- not sure if I want to risk it again. No matter how much people are saying how good it is now, it's hard to muster up the effort to move again.

EDIT: Perhaps I wasn't clear enough. Back when Firefox was saying it's as fast as Chrome without being multi-process. They were saying that it's better. I tried. I moved. I got f*cked up. I move back. Twice. You'd excuse me if I no longer believe what the Firefox dev were saying about their browser.