But what about the bad things videogames do to you?
Here's the thing, and I realise other people have said this before and better. Videogames have ratings, just like movies. Games containing content which could influence undeveloped minds cannot be sold to or bought for such youngsters, and if the youngsters still manage to get hold of them and play them, that's the parents' fault, and game developers can't be held accountable for the consequences. Of course, it could be argued that videogames are just as bad for, e.g., 21-year-olds, so let's address these concerns.
I would like to echo the words of Ctrl+Alt+Del and stand up and say: I am one of tens, perhaps hundreds of millions of people who has played violent videogames, enjoyed them thoroughly, and went out and did not kill anybody. In the words of Bruce Schneier: don't start worrying about something until it ceases to be newsworthy. Videogame-related deaths are national news, because they happen maybe yearly. How about car accident deaths? There were 38,253 fatal car accidents in the United States in 2004. Which of these should we be more worried about? If you have a situation where a violent videogame can incite an adult to kill - chances are, that guy was insane already. He could have been tipped over the edge by a videogame or a movie or a television show or a rough breakup or a bad day at the office. The vast majority of individuals are level-headed enough to tell the difference between reality and fantasy.
Which is I guess the main point. Videogames are there to provide escape from reality. They allow us to do things we can't do in real life - drive fast cars, save the world, shoot bad guys with impunity.