The more I know the dumber I feel when I make a stupid mistake.

It isn’t that I am dumber, but I do feel dumber.

Hold my beer.

I may not be dumber than I was in the past, but when I was dumber I may not have had the ability to know how dumb I was being.
If I’m smarter now I may know how dumb the mistake I’ve made is and therefore feel dumber than I have felt in the past.

I’ve been dumber, but that was when I felt smarter.