The loss of users happened when Chrome came out. At that time Firefox was eating tons of memory and getting buggy with more tabs open. Chrome was also marketed very aggressively by Google.

Firefox partially removed those problems with later versions: it stopped eating so much RAM.

Sadly after version 56 the "batshit insane" strategy started. It's like a set of terrible decision after terrible decision. (1) alienating users by killing extensions (2) constant changes to UI, workflow (3) 1 year later forgetting to sign extensions so everything stopped working (4) patching everything via strange side-channels that shouldn't exist (5) even more batshit insane changes to browser, killing extensions AGAIN and chaing extensions again

If all those things simply did not happen and Firefox was simply maintained like a normal program, their unique selling point would be "our product is similar, but offers you your favorite extensions and also we don't spy on you". That would be their secure niche, from which they can expand and which they cannot lose.

But they do everything they can to lose their users.

> Chrome is stable because they don't really seem to do much from release to release, and that _works_ for the average user.

What is the value add of constant shifts of Firefox? Definitely not security.