When someone, wallowing in self-pity, blames their own failure on themselves, you must explain to them how they are blameless. After all, they and everything they do have their causes which stem from beginningless time. No-one can change destiny.
However, when they blame others, then explain how the fault is their own. It is at least their responsibility to get others to take responsibility.
Karma
Never say "I am too deluded for there to be any chance of my becoming wise." For the smallest of seeds can grow into the largest of trees. Once a cause is created it is never lost, even though it may take a million years to grow and reach fruition.
Use reason, then have faith: this is always the process. You must come to understand cause and effect fully, or you will fail to break through the Barrier and will therefore believe your efforts are in vain. Break the chain of karma, or you will remain a fool who believes in death.