Thats cos you probabally have a job, and think of all that money that you could save instead of paying for WoW monthly, you could soon save up and buy a new computer, or a new game for that matter
But the thing is, if KotOR3 where to become a Multiplayer game, there would be quite a few people who would just buy it for its multiplayer reasons, because they may have heard about it somewhere and just decided to get it because of multiplayer without acctually getting the whole understanding about it, which is fine... to a degree.