Proverbs 26 is pretty hard on the fools. Verse after verse (10 of the first 11) give various comparisons that make it very plain to all that a fool is not something you want to be or someone you want to spend any time with.
But look at verse 12
12 Do you see a man who is wise in his own eyes?
There is more hope for a fool than for him.
Wow! A fool returning to folly is compared to a dog returning to his vomit but there is more hope for a fool than a man who is wise in his own eyes! I'm not even sure what I can say as further commentary. Perhaps that is because someone who is wise in his own eyes can't be taught anything, can't be bothered with facts or truth, doesn't listen to reason. He already has all of life figured out (in his own mind) and because of that, there is more hope for a fool.