Have a single age restriction.

I am an 18 year old man. Although legally I am, I still do not feel like an adult. There are many laws in order that still restrict me due to my age. If I am an adult, why is the government treating me like a child? Can I not make my own decisions? I have the ability to drive a car, a very dangerous vehicle, and vote for the leader of our country but alcohol is off limits? I can not purchase a handgun but a rifle is okay? I wish for all laws restricting age to be the same age. Either make the age 18 or 21, the age itself is not the issue. The issue is that many "adults" can not do what they wish, due to the stereotype, that anyone young is irresponsible. Let the actions of an individual be that person's responsibility.