Ponzi has 100$ and up.
I just want create btc web wallet where users can deposit some funds if they want(10% month, thats just number)
thats is like bank, where you open you bank account and if you want you can deposit your free funds to saving account.
You cant fabricate 10% of bitcoins out of thin air, like banks do. That is the point of BTC.
If you want to replicate banking models, then become a bank.