Very recently, some Smart Contract Income Opportunities have become popular. Most of them involve Person to Person transactions where you pay 0.1 ETH to your upline and you receive 2 payments of 0.1 ETH when you sign up 2 direct referrals or you receive them via spillover.

They are promoted as risk free, decentralised and members in full control.

My question to the knowledgeable ones here is, can such smart contracts be manipulated where the owners of the program can divert a transaction to their address?

Also, can the owners of the programs end the smart contract whenever they wish and run off with money acquired by somehow diverting several hundred transactions to their address.

Please help me understand the reality of such programs, thank you.