Depends what you mean by "just a matter of money". If you could enslave the entire population of Earth to work full-time on the project for a couple of decades

Depends what you mean by "just a matter of money". If you could enslave the entire population of Earth to work full-time on the project for a couple of decades or so then, yeah, you could do it easily. In a world of free will and competing priorities I don't think it'll be possible until we reduce our cost-to-orbit. Certainly there are no big technological show-stoppers though. As a vague guesstimate, I've read 1km proposed as a minimum viable radius for one of these things. So you'll need a rim about 6km long. The International Space Station is about 100m long, so if you staple sixty of those end-to-end you'd have a minimum-viable 1g station, at a cost of about six trillion bucks. But of course it would basically just be a thin tube, not much living space. As for asteroid miners: I can't possibly imagine that this is the sort of thing that we're ever going to send humans rather than robots to do.