I've left bands for good reasons and for petty reasons. Sometimes good moves, sometimes not, but learning experiences.
Among the petty reasons, usually in my early years of playing, were personality conflicts. Sometimes someone else would quit and I just couldn't gee haw with the new one.
Sometimes a band would decide we needed another member. more people that I really didn't bring anything to the table, but took an even cut with no new increases in pay, nor new gigs.
A couple bands I really liked were bad about booking far off for very little compensation, just couldn't afford to play, as much as I liked them.
More petty reasons on my part were I didn't care for all the significant others and their input. I still run into that but just deal with it... I've accepted that'll never change.
Sometimes I just really wasn't enjoying it, didn't really like the music because of a limited song list or just grew tired of something I probably shouldn't have gotten involved in.
There has been quite an evolution in how I view things. Stuff that would've made me quit in my teens or 20s seem small and silly now.
Apart from the current situation we are all in, I'm still in this band, dealing with conflicts that crop up from time to time.
I see now that if I just bide my time, many things resolve themselves, at least to a tolerable level.
I now step back and look at it all objectively... I wish I had seen things differently back when, but what would I have learned? I am who I am because of who I was...