Many people are lonely... especially in Asian markets. Many "nerds" and fanboys don't talk to girls and of course, don't have relationships.
I've been dating various girls this past few months, and *STILL* feel lonely without having a regular girl to hang around with (ie: a Girlfriend ). Even thou, there is sex with some of these women.
So for the guys who are still virgins or very rarely have sex or GF, that problem would be much much worse. Hence, you also see these games like WOW being used by so many people as its a substitute for real people in real life.