I ended up getting a job as a game producer thanks to Quake. I was playing online in a clan, and was one of the worst in the group but having fun. To help my score I "cheated" by figuring out how to modify the models in the game, and then adding the rocket attribute to all the player models. This caused them to smoke when they ran (pretty funny) and more importantly glow in a way which allowed me to see them when they hid in dark areas or were just around the corner.
This was long before Punkbuster, wallhacks, or any other cheats. The result was I played a lot better. One of the guys in the clan found out what I had done, and his father owned a game development studio. Next thing I know I was on a plane for Silicon Valley and working as a game producer for a few dreamcast and playstation games.
Unfortunately I was only able to continue to work until my life savings ran out. Yes the jokes about eating Tap Ramen are quite true. I was making only about 70% of what I needed just to cover basic expenses. When I asked for a raise I was told in no uncertain terms that there were plenty of other kids living with their parents who would gladly work for what I was getting.
I'm now a sysadmin living in the midwest making about 3x what I was making in the games industry, and my mortgage payment is less than the rent on my studio in Silicon Valley. I love what I do, but am really glad I took the opportunity to work in the video games industry. Have I thought about writing something on my own, sure I have. I even have a couple notebooks with fully fleshed out game designs. And I have time to do those because I'm not working 90 hours a week on somebody else's game.
So my advice for somebody wanting to get in is simple. Do something, anything, to stand out from the other potential applicants. Find a game you enjoy and mod it. If you're into graphics, find an open source game and help them out (Open source games are notorious for needing graphical help) Write flash games, make something with the XNA. In short, just do something. You'll find out a lot about yourself, and if you have the drive and dedication necessary to make it. Set yourself timelines, make milestones and meet them. But most importantly, do SOMETHING.