Unhealthy in what sense? Is it any more or less unhealthy than a pro football player practicing to the point of injury so he can make top $ at his sport?
It's a market, just like any other. Just because it is nothing more than entertaining to the average lay person does not mean it is unhealthy or invalid. Other examples of officialy recognised sports that cause real physical damage are boxing and other full contact sports. Are those unhealthy too?

I think anything that causes personal life to become unmanegable is unhealthy. As for the rest, if they can be successful at it - more power to them. They have found a way to make money and get sponsorships playign video games then they have tapped a market that for many is a lifelong dream. Good for them I say.