Pride is a very common failing, I believe. By all that I have ever read, I am convinced that it is very common indeed; that human nature is particularly prone to it, and that there are very few of us who do not cherish a feeling of self-complacency on the score of some quality or other, real or imaginary. Vanity and pride are different things, though the words are often used synonymously. A person may be proud without being vain. Pride relates more to our opinion of ourselves, vanity to what we would have others think of us.
A killer normally commits twenty errors, but is only aware of a third of them. Most of them are due to carelessness or inexperience. But there's one type of error that we can consider deliberate. It's a sort of signature. "The devil's dumbest sin is vanity". But where's the fun in being the devil if you can't let anyone else know?