Music gear is, in many ways, even worse. My SO plays guitar and I play drums. Sure, you can only play one guitar at a time, but those pedals are a rabbit hole, and I try not to think about amps and mods. Don't even get me started on cymbals. With an instrument that is a bunch of instruments, the only limitation is the size of the practice space.
At least I can only ride one bike at a time, which keeps things in check a bit. Five bikes seems sufficient...so long as I don't take up MTB, BMX, fatbiking, or cyclocross...