Luke 16:30

And he said, Nay, father Abraham: but if one go to them from the dead, they will repent.

So here it comes out. The rich man thoroughly understood why he was in torments, even if the commentators cannot seem to get it straight. It was because he would not repent. As Miller put it:

The rich man's desire that his brothers repent indicates that he had discovered that he was not in hell because he was rich, but because he had failed to repent of self-lordship and place himself under the Lordship of God.[44]

It was not what the rich man did that landed him in the jail, but what he did not that landed him in hell.