That can be a good idea. And honestly, what can it really hurt?
There is a lot of alcohol out there, no doubt about it.
And you’re right. As a non-drinker, you will become the default designated driver at a lot of functions. Some people don’t like that, some people don’t mind. Some of your friends might even come to expect it, even take it for granted, which can be frustrating.
On the other hand, some of your friends will greatly appreciate it. They’ll come to know that you can be trusted to not drink, and will be confident in putting their safety in your hands. (I even have one friend that will generally only drink if I’m out with her. She told me one night that she didn’t trust anyone else to take care of her, and make she she gets home safely.)
My experience is that no one will treat you like an outcast, but there may be rare or occasional times that you feel a little out of place, or on the edge of the group, looking in. Usually this seems to happen when everyone else is drinking very heavily. . . and sometimes that can provide more than enough entertainment to keep you from feeling “off”.
You might as well give it a shot. I’ve personally found a lot more positives than negatives with not drinking.
As a little background, I’m in my late 20s, and I haven’t had more than a drink or two a year since I turned 21 (on rare special occasions, I’ll indulge in something small, like a glass of wine at Thanksgiving dinner with the family). I’ve also moonlighted as a bartender for over three years now. And, nearly all of my friends drink to some degree.
Anything I say here is related to my own personal experiences, so yours may differ.
I can’t think of any occasions where I was treated differently, or felt uncomfortable, or anything like that. Sometimes people are curious as to why I don’t drink, but no one has ever teased me about it, or tried to convince me to drink (with a rare occasion when a little peer pressure slips out to try to talk you into taking a shot with the rest of the group, or something like that). Most people tend to respect your desire to not drink, and even admire it.
I have also noticed that as I spend more time with them, some people will even adjust their drinking habit slightly. I can only assume it’s due to association with me. I can think of a few friends off the top of my head who don’t drink in as great of quantities, when they’re out at a bar or restaurant with me, as they did when I first went out with them. People who used to have half a dozen drinks in a couple of hours, now will have just a few. And when it’s a smaller group, or just me and them, they’re as likely to not drink at all, or limit themselves to just one drink.
I believe it has to do with the influence that we all exert over our friends and associates behaviors. If you go out with a group of people who drinks a lot, you’ll tend to drink more. If you go out with a group of people who drink less, you’ll drink less. And when you go out with someone who doesn’t drink, it’s easier and more acceptable to limit yourself to only a few drinks, or even none.
Humans are very social creatures, and we all tend to crave acceptance. And there is a strong desire to “fit in” with how everyone else is acting. I should note, however, that the opposite of what this whole thing is also true. There will be times when you will strongly desire a few drinks, especially when everyone else is drinking. Sometimes it’s hard to stand apart and not drink.
You can always look at it as a challenge to be different, to be individual. It’s often easier to resist peer pressure, even when it’s unintentional, that way.
Depending on how much you drink, and where you drink, you might be amazed at how much money you save, too. You can drink at home for a modest amount, but when you go out to bars, it’s very easy to rack up a $30-$50 bar tab without blinking. And the more you drink, the harder it is to remember how much you’ve spent.
It’s a lot easier to drop $5 on a all-you-can-drink water/ice tea/diet soda (I know, those will usually only cost you about $2 (or nothing for water) but I like to tip well) than $50 for a bunch of alcohol. Think of all the protein powder that would buy! 
As a final advantage, it’s safer. Many people are good about not drinking and driving, but not everyone is. If you don’t have a designated driver, and you have a few more drinks than you’d planned on, it’s a rather embarrassing situation to be in. I can’t count the number of times I’ve seen people who were borderline unsafe to be driving, or even borderline drunk, and who drove anyway. Trying to talk someone out of drining in that condition is often impossible. You make any comment, and they take it as a challenge to their proficiency as a human being, or a challenge to their ‘manhood’, or whatever. Some people are insulted that you’d even suggest they might be incapable of driving themselves home (even though they’re having trouble walking to the door).
Most of them will make it safely home, true. But if anything unusual happens, they are not at their best for handling it. That little bit blurred awareness, or little bit slower reaction could mean the difference between life and death.
You can probably tell by now that I’m all for being alcohol free. I’m quite happy that way, and I think it’s a great way to live. But I’m also a realist, and I do believe strongly in personal choice. I would never force my choice onto someone else.
Heck, you might try it for a few months and decide that it isn’t for you. If that’s the case, then so be it. It’s your life to live. You might even decide on a middle ground, of moderation. A beer at a BBQ is fine, but a siz-pack isn’t. A glass of wine at dinner with friends is enjoyable, but maybe a whole bottle isn’t.
The key is to find what works best for you, that allows you to live a productive and enjoyable life. If you’re not productive, you’re wasting your time. And if you’re not enjoying life, then why the hell are you living?
Good luck!