Being sarcastic or dismissive of concerns isn't the way to deal with that type of criticism which was my point. Not that maxkleins criticism was valid or well based that said however, saying "yeah look how the existing banks" have done doesn't tell us anything about how you plan to better that and doesn't really say much at all since for the most part and most of the time the traditional banks do really well.

He didn't actually give any information on what their plan entails that would remove doubts. They've said their money comes from two places loans and cuts from credit card fees. While what if they have a bad run with their loans/investments(like big banker banks) or not enough people use there credit cards? That makes them just as vulnerable as the existing banks so saying existing banks don't work doesn't tell us why you will.