[...] Can't anybody build anything that will last more than a few weeks? Am I that old to believe long tern stability is a good thing?
Good thing Mozilla does just that, eh? They pick one of about every seven major-version Firefox release to make an ESR (extended support release) version, and they have been doing this since 2012. The ESR release is supported for one full year, plus another couple months or so (specifically, the time it takes to release the next major version of Firefox after that on which the last point release of the ESR version is based--they add critical fixes from major versions to ESR versions during the year of support but avoid major feature or UI changes).
This is intended for organizations that deploy Firefox and need some stability (e.g., to test something before deployment and ensure support longer than 6-8 weeks), but you can use it at home, too, if you want.