I'm 18, addiction won't get me for years, so what's the big deal about having some fun?

Hmm: Many people that have serious addictions will say it started out as fun as well, obviously there is a reason people use these substances in the first place and "fun" is definitly one of them. I suspect if most addicts could do it over again they would say "not worth it". You may not get addicted this is true, but by the tone of your question, it is also possible that you already are. Try sober fun.

Ur Actually Wrong: You are much more likely to develop an addiction at 18 than at 26. Your brain is much more susceptible chemically to the development of addiction the younger and less developed it is. It is hard to believe, but your brain is still going to develop much more if you don't poison it sooner.