Decadence permits opportunity, it's sort of like that Lincoln quote, "if you want to test a man’s character, give him power". There's probably a lot of people who would be on Epstein Island given the opportunity.
More than that though, being rich robs you of character building and idle hands are the devil's playthings. If lounging around in luxury you'll no longer be stimulated by the ordinary, seeking more taboo interests to whet your appetite.
Ultimately is comes down to religion, humans are flawed and sinful, and without a foundation of principles to stand on you're adrift in a sea of your own whims and shaped by your culture (which is the only reason moral people exist, they're raised in modern times tamed and shaped by Christian morals; essentially conservatives who aren't Christian but still hold largely the same views is due to residual religious influence).
Tldr; People are sick and need God.