I've thought the same thing myself. The returns on offer as you move higher up the VIP levels are incredible - I'd love to know how CP is able to offer this.
Up to over 50% APR, quite impressive and unbelieveable at the same time.
But since CP has already existed ages ago, I believe the model is sustainable since it spurs the usage of their faucets, and surely some fees are involved when it comes to exchanging between the tokens and cryptos. Win-win I guess.