Why would they return it? Backing something is like an early purchase with risk and discount built into it. You are not an investor. All you are ethically​ owed (and not even legally) is the game with the stretch goals you backed. If they blow past the stretch goals they can keep the money if they wish.

How big a 'cut' does Roberts himself take as well? Given this endeavor is built entirely on the charity of the backers, I would really hope he isn't taking a percentage, but sadly wouldn't be surprised either if he is.

Why wouldn't he? All you are doing is buying something unreleased for a discount because of the built in risk. He gets to do whatever he wants with the money left over as long as he meets the stated goals.

I think many people would argue that ethically/morally it's somewhat questionable - he's taken donations, not investment, and as such lacks any of the oversight/due diligence external investment usually attracts. Similarly, I doubt even a majority of backers actually understand the business/charity model they are putting money into - that we are now at 9 figures certainly suggests these are not "sophisticated investors".

Was keeping a large amount of the cash for himself a stated goal? probably not, hence my curiosity. His business occupies a grey area between business endeavor and charity. Me in his shoes, I'd sure as hell feel bad taking a chunk of the donations. I'd have no issue with him pocketing the profits of traditional sales, should he ever reach that point - no one who donated was under the illusion a return would occur, but they should perhaps quite rightly expect that their donation at least pay for development, not lining Robert's pockets.

I think it's also debatable the extent to which backers have "bought" anything, let alone received a discount.