Unpopular: paying tithe from a salary you cannot feed on is fear, not faith. Agree?

I say this as a person who grew up in church and still prays every day. A man told me last Sunday that he pays 10% and now his children eat once a day, because God will restore. I asked him who told him this. He said the sermon. I am not against giving. I am against giving what you owe the shop. Tell me where I am wrong.