Why is he a total jackass? Just out of curiosity.
He thinks very highly of himself...that's the problem. A huge ego that crushes everything it comes in contact with. I mean...he charges people to get an autograph...jeezus.
As an example, he apparently thinks that he "owns" the name "Glamorous Glennis", and makes claim to any aircraft that is painted up as his mount. Jack Roush used to have a Mustang painted up as GG, and Yeager essentually forced Roush to let him fly it. It got to the point that Roush repainted the aircraft as "Gentleman Jack" so he didn't have to deal with Yeager anymore.
I know of several "wannabes" (myself included) who have approached him casually at airshows just to say hello, and have been unceremoniously brushed off...and then insulted just to rub some alcohol in the wound. I know of kids who have wanted to get their photos taken with him at airshows, and he says 'no'.
Just overall a douche. Which is really unfortunate, because a man of his accomplishments doesn't have to be such a cock. As someone mentioned, Hoover has many of the same accomplishments, and is a complete gentleman.
I might...might...p*ss on Yeager if he were on fire. Chances are he wouldn't even stop to look if I were on fire.