Some people believe in superstitions because it gives them something to base some of their actions off of. Another reason is because that is the way they were raised, and some things they don't bother to change. Many times people KNOW that the superstition isn't logical or true, but they choose to believe anyways.
This superstition doesn't have anything to do with wisdom and reason, but rather this superstition cannot be removed from the heart, brain, or conscience of a human being.