I made the mistake of buying a wool baseball cap once. It's as bad as you'd expect.
It's honestly hard to imaging why one would ever want a wool baseball cap.
I only bought it because it was the only one they had that had a buckle clasp and not Velcro/some other BS.

A WOOL baseball cap.
That fucking traps in heat.
That collects dust/debris like nothing else.

Very bad, would not recommend.