I’m one of those. If I’m only one of 200 (as in, 199 don't care) and if Firefox has 200 million users, Firefox will waste millions of hours of user’s time per each additional release.
Even if it's just a matter of reading the release notes, having to do that twice as often is a non-zero burden.
Of course there is Firefox ESR but I seem to remember Mozilla's website basically explicitly recommending against it with language along the lines of "This is only for people whose corporate policies require it, don't install it unless you have no other choice."
Do you actually do this? Do you think the percentage of users who do exceeds 1%? I mean, I do read the release notes for new web features but that’s because I know from the stats that almost all of our users will be updated shortly after release.