YOU ARE ONLY LOOKING AT THE LIFE OF KARNA, BUT WHAT ABOUT THE LIFE LORD KRISHNA?
HE WAS A NON-KSHATRIYA, BUT HE BECAME KING, AND INFACT, HE PREACHED TO THE WROLD AS A BRAMHIN, WHO KNOWS OR REALIZES BRAMHA.
AND BY THE WAY, THOSE WHO SHOWED DISCRIMINATION BASED ON BIRTH OF A PERSON, SUFFERED FOR THEIR MISTAKES EVEN IN MAHABHARATA TIME FRAME. LOOK AT DRONA, WHO BY SHOWING SUCH DISCRIMINATION, HE INCURRED CURSES, WHCIH ARE THE VERY REASON WHY HE FAILED.
Donot only look at one side of the coin or use half-knowledge to create confusion among people.
Indian society is slowly, but steadily coming out of the Birth based (wrong one) caste system, and is looking towards the Character based (ORIGINAL) system. The more India does this, the more India develops.