Use is a slippery term. An economist would tell you that it has to have some use to you or you wouldn't have bought it - even if its use is just the psychic utility of having gotten a bargain. But I gather you're talking about something else.

I have bought bikes because of the price. With some I've been surprised at the ride quality and wound up keeping them, at least for a time. It's good to have a couple spares to loan out, or so you don't have to panic if your main ride is on the workstand waiting for a part. But once I have that covered, and a couple favorite riders, I'd just as soon sell it and move on.