It's not only this, every thing like this is a scam. Real staking with real earnings can be found on decred and soon eth and nothing else at moment and even then eth staking will be risky if you dont understand how to do stake properly. Truth is, easy coming, easy going.
Why do you think it's a scam?
Tether (USDT) belongs to a new breed of cryptocurrencies called "stablecoins" that aims to keep cryptocurrency valuations stable. All the staking operations and reward payments are governed by a smart contract. The rewards are generated and transferred automatically and no entity, be it Tidex or any other, can meddle with them.