Why is Karna a failed "hero"?

Character of Karna has always fascinated so many people. Karna is a very powerful character in mahabharat (abandoned by his mother Kunti and embraced by Duryodhan- the villain in mahabharat).
Karna had all the qualities to succeed - in fact he was much better than all the other pandavs.
But still he fails.. and the question is why..

I dont think it is destiny or his friendship with Duryodhan that led him to destruction.
I think it is his own nature that wreaked such a havoc on him.

Karna never learnt to go back.. take a detour..
Even when Krishna repeatedly advised him to join the pandavas.. tell them the truth about his birth.. he denied saying he has learnt only one thing in life.. never to go back.. always follow one path like the ray of sun..

And that my friend caused all the problem. Plus he had other issues too..

I think the reason why he failed was because no one ever dared to tell him the difference between right and wrong.
The day duryodhan offered kingship to him.. he accepted it..
He also took part in all of Duryodhan's evil plans like disrobing Draupadi (the daughter-in-law of royal family), chasing padavas to the forest etc. etc.

I think it is very important in life to have a guiding force... someone who can guide you to right direction.. someone who can save you from the agony of deep regrets..
And another thing that is more important than first one is the presence of mind to take a detour and correct your actions..

This blog truly summarizes why Karna is a failed warrior.. but not a true hero..
http://pushti-marg.net/bhagwat/karna.htm


More later!