ADA (Cardano) is one of the most popular cryptocurrencies. It is trying to compete with Ethereum, supposedly having better technicals (low fees etc.). The author/main developer is a jew though (Charles Hoskinson). Anyone has any guesses what his game is here? Is there a secret backdoor in the code or any other shady scheme going on?

Cryptocurrencies are Gambling devices not investments. It's mostly worthless in reality. However not saying someone can't make money in the short term on one of them. Just know when to pull out and don't push your luck.