I try to keep the numbers down, though I do a lot of different riding, so I still have 4 bikes: Fat, FS MTB, Gravel/Road, and utility/errand.
If I lived somewhere with a much shorter winter, I’d probably lose the Fat bike.
I’m the same way with music. I have one electric guitar, one steel string acoustic, one classical. One electric bass, one standup.
I know some musicians who will have multiple electrics or acoustics, but I’d rather just work with one.
Maybe if I was a pro, I’d have backup instruments or bikes.