> devs will not optimize of it.
Yep.
I have been a FF user since.. well, Netscape. Yet, FireFox-specific bugs have always been a lower priority.
Because, it's "a bug effecting 100 users" vs "a bug effecting 900 users"
When you consider FF users are harder to monetise (admit it, we generally are), you can start saying "a bug effecting ~50 potential customers, vs ~800".
*(fortunately, now that IE/Edge is out of the picture, those types of issues are rare)