[Glyptodon]

I disagree with this - plenty of people treat stock as just wanting a share of profits/ownership and not as value speculation. That said, I do think we should be making rules that devalue speculation, perhaps turn-based trading since there's no particular benefit to the world from high frequency trading or value discovery happening in 5 milliseconds instead of 5 seconds, and making it so that being publicly traded requires not having controlling owners or preferential share classes.

Edit: and with prediction markets you don't own anything. Even with commodity futures you can end up having to take possession of cows or something.