Vanguard_Ex said:
...because gaming doesn't have to be done 24/7? That's like asking why someone who is married is out having a walk instead of having sex.
Pretty much this. You don't use consoles 24/7, we don't play PC games 24/7, and that was an incredibly stupid question, to be quite honest.
Besides, some of us use our PCs for work too. I'm in a university course for Game Design, and I need to use my computer for C, C++, C#, Java and various other kinds of code, not to mention written work or just general research.
Computers are a little [http://tvtropes.org/pmwiki/pmwiki.php/Main/Understatement] more multi-purpose than just for games, you know.
Hell, even consoles can be used for more than just games; playing DVDs or music, for example.