The web isn't the best place for this kind of discussion, the main reason being that different cultures treat alcohol very very differently. Much of Europe doesn't have a minimum drinking age, yet they tend to have less binge-drinking than the US. In Australia 18 is the legal age for being on a licenced premises, but it's pretty much accepted that you'll be drinking from your mid-teens.
Personally, I think the countries that don't have a legal age limit have the most sensible attitudes, and the statistics on alcohol-related injuries across nations backs me up on that one. But you can't just take that and apply it to a different culture - people seem to grow up more slowly in the US, and at 21 you guys seem to act when drunk like we do at 17-18.
Also, the US has some seriously puritan attitudes towards alcohol, and people will react differently there than other countries. You can be a complete non-drinker in the US without people getting wierded out by it, or it affecting your career. In Australia, I find being someone who rarely drinks to be a constant problem with work (I'm a lawyer, my wife is an engineer). At the firms I've worked at, there's a LOT of top-down pressure to go drinking after work, especially on a Friday - to the point where being a non-drinker will seriously hamper promotion prospects.
On the job interview boards I've sat on, I've repeatedly noticed that one of the main things my colleagues look for when hiring graduates is whether they'll 'fun to work with', which means 'will he/she come drinking with us on Fridays until 4am'. I've always tried to discourage that, but it's so common that people don't seem to see what's wrong with it (note: the public service over here is an exception, it wasn't like that when I worked for Legal Aid, just at private firms).
Now you can see why in that kind of culture, being a non-drinker isn't necessarily a good thing - not that I'd advice starting at 15, but most normally socialised teenagers here would be drinking by 17 at the latest. Again, I don't necessarily think that's healthy - I'm just stating the facts as they are. In Australia, non-drinkers on average earn around $8,000-10,000 less per year than ALCOHOLICS (!!!), and a whopping $15,000 per year (less for women, more for men) less than moderate drinkers. Social inclusion affects career success - I hate that that's the case (I'm someone who would greatly prefer to go straight home after work, and if I'm going to go drinking, to do so with my actual friends rather than work colleagues), but it's just the way things are.
From what I gather, the US has a more conservative attitude to alcohol, so you can't really take that and apply it to wherever you are. So I'm not saying 'read this, and go drink' - I'm saying that you need to talk about it with people from your own culture, not on the global internet.
Fact is, whether we like it or not, we're all products of our respective cultures. You can't go out and expect to be able to drink at 15 because the French kids are doing it, when you've spent your whole life in a country where people don't drink until 18-21.
Personally, I'd say do what you're comfortable doing and no more. Don't get uppity at the kids doing the things that you aren't, or you'll just end up very very disappointed. Frankly, individual sensibility has a miniscule effect on where you end up compared to parental wealth and education opportunities - there's plenty of teenage junkies who end up in law firms, and plenty of well-behaved kids who spent their whole life working hard only to end up still working hard in a low-paid job. I was a rabble-rouser as a kid - did all the drugs, all the partying, and I'm in great shape with a great income, a great marriage and never had any addictions. If lived the same life but came from a working class background, would I still have done as well? Of course not! Some folks will do everything they can to risk their good fortune for a night of fun, and get away with it - so don't base your decisions on the certainty that you'll end up better off than the kids that do the wrong thing (on the other hand, studying hard will always serve you well - even if you don't get a better income from it, you'll always appreciate having the knowledge, and more importantly the mental skills, you get from it).
Do what you feel comfortable with, and from what you've said you're already decided that you don't want to drink. So don't. Just don't wait for the world to reward you for it beyond the satisfaction of living the life you want to lead. The world just isn't that fair.
