You know I wasn't quite thinking of it like that.
I think while you're in the interest free period, the concern wouldn't be there because even though you're making the initial payments, you acquired tangible assets. These assets, at least for me, give the security that the retail purchases i'm making through crowdfunding are still valuable. I consider this to be the worst case because you wouldn't have to worry about reselling at all until the brand you supported failed and you, as one of the people who purchased the inventory, voted to actually receive instead of liquidate.
As the card loses that interest free period, you would want to decide if the cashback, miles, whatever it was you wanted was still good for. As in if you feel comfortable making the payments (which I feel as though you never should should try and hack what you can't afford if it all goes wrong) then you choose too with the full awareness that you're earning cashback or miles and the profit from the brands selling your inventory.
It this was a loan outright, I wouldn't personally wouldn't feel comfortable with this. I tried it once with p2p on credit and it didn't work the way I wanted, in fact I think that platform closed down shortly after (this is about a year or so ago). I only feel comfortable though because well I'm getting assets, which add that security I was talking about. This security is further cemented when the brands have purchase orders. Barring a rogue wave, somalian pirates, or the ship just getting stuck out there, I know the inventory will sell after net terms once it reaches the U.S.A.