Why did Heretics appear in Christianity?

The church at that time had a very large influence in society, but not everyone could share her views, especially if they contradicted common sense. So heretics appeared because some people were actively denying the actions of the church and its organizational form. At that time, the church was incomparably wealthy in relation to everyone else. The clergy lived in luxury, and all the people were encouraged to live in poverty. Also, many priests explained certain texts from the Bible exclusively in their favor.