I've seen interest bearing crypto accounts. You can get 6% APY on stablecoins. Any project that promises you more than that is calculating APY for the current day or hour. 40% APY for less than a single day is just misleading advertisement.

Although I am generally against cryptocurrencies, I cannot be against the idea of building a decentralized banking system (cryptocurrencies are merely cash). I mean, if we get to do it with fiat, they surely deserve to do it with their cryptocurrencies.