I would imagine it's because the utility of owning your own isn't precluded by the cost. If I can spend 200 bucks and get a shitty electric lawnmower that prevents me from having to deal with my asshole neighbors, I'm going to do it.

If I want a laser engraver, four axis CNC mill, and a lathe, I'd be a helluva lot more willing to put up with other people's crap if it only cost me 45 bucks a month for a membership to the shop.

I suppose there's some break over point where the cost of the device, its utility/convenience, and its inherent specialization provide enough incentive to distribute its cost and availability over a larger group. Successful businessmen would figure out what that line is and capitalize on it. Engineers figure out how to live without it or how to make one on their own.