The sin that is considered the worst is pride. By that, they mean this is the one that is at the root of all of the rest. Pride is what makes the other sins possible. Pride, at base, is nothing more than good, healthy self-love. Therefore, I am worthwhile.
Few understandings are more valuable than that.
The problem occurs when healthy self-love escalates out of control. Pride keeps us from getting the help we need. I can handle it on my own. I don't need to consult anyone. I know how to do that.