The 10 mil coins is a way that a low level player has a chance of getting something extra from the fight. I will grant you that the the stronger players have a better chance of getting it because the damage that they do on one fight can kill him when other players will need more that one fight, but if the strong players can weaken him enough where a weaker player can kill him him while the stronger players are in cool down.

Think of it as a lottery for the big prize where the stronger players have more tickets that the weaker ones. I see nothing wrong with that.