My idea was primarily based on my experience is something like this:
I know (meaning I know what they use) around 15-20 devs on MacOS.
Almost all of them have FF installed. Some may open it occasionally but just as an alternative to open in private mode or check some weird behavior to see if it is cross-browser or cache related.
- personal usage: except maybe 2, all the others are using Safari (most of them) and Chrome few
- professional usage: except for the same 2, here I think Chrome is more used and Safari less
Thus in these developers' case, I don't think they will recommend FF to their friends or relatives even if FF is installed on their machine as it is not their daily driver.
I am in the same category regarding usage: I forced myself multiple times to use FF. Still try to do that couple of times per year.
But fallback to Safari because the battery lasts so much longer and because it is integrated with the MacOS keychain.
One might think that with M1, people might afford to lose a bit of battery but it is the reverse. Seeing how long it lasts one barely thinks of cutting those hours short :) Could mean starting to carry again the power adapter or always looking for a table near a power socket.
Here is a browser that I installed not long ago and start to like it more and more: https://browser.kagi.com