Nailed it... "ownership turned out to be largely a hack people resorted to before they had the infrastructure to manage sharing properly"

Ownership is just an idea to align consumption with stewardship. The idea that owning stuff is "right" or "good" is just a cultural phenomenon, and not one shared by all cultures (e.g. Native Americans).

I think you could do a lot worse in trying to find a start-up idea than to ask yourself "where is there excess capacity that can be shared."

Parking, housing, office space, cooking, people-to-do-tasks, storage space, server space - this is the sharing era.