I think that this t-shirt image from CTRL-ALT-DEL puts it best:
Games do not make violent/bad/murderous/ect ect people. It may be a contributing factor, but in the end, its the person who decides to do those things, not the games.
as for that comment that "All gamers are bums", he's more then likely coming from the school of thought that a hard days work comes from actually breaking a sweat and doing physical work to make ends meet, instead of say, competing professionally in video games and making a living off of it.