In grade school, I would not admit mistakes. Ever. As Zetetic pointed out, it was a good way to invite additional torment. If you stood your ground, you looked douchey but you never conceded and so the frustration was less.

In college, I admitted mistakes frequently because admission of mistakes actually brought benefits instead. People didn't torment you and your admission opened up new pathways. Being humble was a pragmatic virtue.

When I left college, I found out that adults are <I>the worst people I've ever dealt with</I>. Status competition was fierce--especially at my government job--and so I never, NEVER, admitted a mistake unless I had planted the mistake for that purpose. If you admitted anything, if you hadn't staged everything perfectly, it would all be used against you. I learned that there was nothing positive in the world, only negatives. Life as a series of demerits until demise.

I think that's why people have hardened so far in their positions, even in private: they have learned that admitting mistakes will bring them harm and learning from them will gain them comparatively little.

Just another reason I live on welfare instead of work, I guess.