I currently have 5 bikes. DH has 3. I regularly ride all except 1, and that one still serves a regular, specialized purpose (plus I'm attached to it).

DH rides all 3 of his at least once a week. He's trying to figure out if he can get it down to 2, but there is no discussion of a single bike in our house

We ride too much, and there's too much of a chance that one would be stolen or need replacement parts. DH commutes on his, so it's to his benefit to have a back up in case of a last minute repair/tire change issue.

CA