Why did the indulgence trade provoke the outrage of true believers?

The so-called indulgences, that is, absolution of sins, were used by some representatives of the Catholic Church only as a means of personal enrichment. For a certain amount of money, such priests sold indulgences to anyone, “forgiving”, thereby, any sin. Naturally, many people did not like this state of affairs at all. It turned out that if you are rich and influential, then you can do anything and commit any sin, knowing that this sin will be “forgiven” you anyway, just pay.