I've become addicted to several games for years, destroying my life when it comes to being social and doing work at school. What the addiction comes from is likely a lack of satisfaction. The skill cap in many games is placed very high, many players won't quit until they acheive a high level of playing, even if it costs them the good things in life. It also can come from being an escape from the struggles of the world, since procrastination is made easier by this. The real only way to get them out of it is to force them to quit. There isn't a real way to remove their addiction. It's pretty destructive if you let it take over life.