While there was for sure a long period of time where Chrome was significantly faster than Firefox, there was never a time where Firefox was particularly bad. Firefox always oscillated between "really good" and "totally ok".
I’ll agree with you that Chrome really changed the web development experience with incredible tooling compared to what you could get back then but this had no impact on most users experience.
I totally remember Chrome being the fastest/snappiest browser, especially the first versions but Firefox has never been slow.
Yes, but guess what the developers started pushing onto their friends who asked for a browser? The one they were personally using.
Word-of-mouth is insanely powerful and FF alienated way too many of the key people.
It was just soooo much better than the competition. I mean, Firefox was better than IE6, but that was not a high bar to pass in the first place. The thing that won over developers IMO was the developer tools: Firebug was slow as molasses and an utter memory hog. And that didn't change for many years - but by the time Firefox caught up, it was too late.