Which means it won't be an alternative anymore and it will die.
Firefox is looking like Apple circa 1997. They can still recover, but they have to focus on what people want.
It would be like using Tor all the time. You know it's better, but the difference in speed is so great, that you have to make a conscious choice. I think I speak for a lot of people when I say that I want the benefits _without_ compromising speed.
Also, Google's pushing it helped. Otherwise consider how Chrome has occupied an IE like market share despite the quality Delta between Chrome and IE/Edge, Firefox or Safari is significantly lesser than the Delta between Firefox and IE was a decade ago, yet Firefox peaked at a much lower marketshare than Chrome's today.
Firefox has a chance at doing the same thing with privacy-aware users and/or power users.
To that end, they need to stop dumbing-down the browser and endlessly playing catch-up with Chrome.