Sure people could spend their time doing something more productive like learning social skills and go to the gym, but as long as they enjoy playing and they don't spend 40hrs a week doing it I think it's pretty unfair to say they're "wasting their life away". Admittedly though, MMORPGs are full of people with social anxiety issues who simply don't function that well socially, so they escape into the world of MMORPGs instead and tell themselves that they are socialising with their friends (internet friends). But the reality is that the day you stop helping them get dragon swords they'll forget you exist and find someone else to bounce memes off of. But to answer your question, MMORPGs games are basically extremely well-designed schedule of endorphin release. They dangle a carrot in front of you, and when you catch it they throw up another one. Even when you've max'd your level and have the best gear. It's pretty depressing.