The fact that evil people prosper is a problem that goes back into the Old Testament. But Jesus said that our Father causes the sun to shine on the bad as well as the good, and his rain to fall on the honest and dishonest alike (Matthew 5:45). The passing "rewards" of evil should not tempt us to abandon good.

The evil person is like the man who jumped from the 50th floor without a parachute. When he passed the 30th, someone shouted, "How's it going?" And the jumper answered, "So far so good." God, we may complain, is always right there to tell us to be good, but he is sometimes rather short on explanations. Perhaps it is because we are not yet ready for explanations. Or, more likely, it is because once we experience deeply in ourselves the goodness of God (Matthew 19:17), we do not need explanations.