Your income in TT Windmill depends on how well you manage your transactions as well as the behavior of other investors. The smart contract, running this Dapp, is completely transparent and every investor will be able to invest their funds honestly.
TT Windmill should not be confused with farms. You cannot sell wheat once you have bought it. The mill will produce flour indefinitely at a starting rate of 10% per day. It is this flour that you can sell.
Once your Metamask wallet is connected to the TT Windmill website, you will notice that your referral address can be copied on the right side of the page. When a new user buys wheat after following your personal referral link, the contract will instantly send you a TT value of 10%.
The only fee users pay — the transaction gas fee. A development fee of 10% is paid to the developer, but this fee is not paid by you as a user, this fee is paid to the developer under the contract as a whole.