Because it is, because eternal suffering is gonna keep your lower self in control when your higher self already rationalised their way into condoning a lack of virtue. Expecting people to be wiser than not is just the silliest thing, don't you know people? There are some who break from the matrix of materialism and hedonism but most never do, and their eyes get bigger and let go of virtue for a moment, and in those cases remembering God's Judgment can save you.