I have four bikes, each for a special purpose, in their order of use - a high end road bike, high end gravel bike, mid level FS MTB, and a tank of a MUT/Greenway bike. All bikes get ridden.
Back in the day I had a couple of fixed gear bikes that would get limited use in the winter, but I'm too old for that.
I'd like a high end hardtail MTB, but I feel guilty that it would take mileage off of my gravel bike.
If it snowed a lot where I live, I'd definitely get a fat tire bike.
Bicycling really isn't that expensive of a sport/hobby. Take up golfing. Even hunting. Or taking a performance car to the track. Or anywhere else you spend discretionary income. And I think the return on investment is great.