He's exactly right. Once you get used to the money, you'll start buying more stuff like a car and then you'll have to work even harder to be able to keep the car. And of course, once you have something, you always want to upgrade it and make it better. I was in your same situation, I've been working since I'm 15. Now, I'm 18, work 2 jobs at about 70 hours a week and take school for 10 hours a week. I get one night off usually. Weird thing is, I have a lot of money, but once you get a bit you always want more. I'm killing myself now, I missed out on a lot in high school, and now I'm trying to make up for it. If you don't have to work, don't. If you really want to, only work 10 hours a week. Any more and your life will start slipping away. That's just from my experience though, from a guy who work 40 hours a week during his High School diplomas. I held a record, which still stands, 8 days straight at 100.5 hours.
Trevor