DRUGS, ALCOHOL, & WHY THE AGES NEED CHANGED

Many people address the argument "I'm old enough to die for my country but I can't drink a beer?" Valid argument, right? I think it is. I don't see why the alcohol age isn't 18 because we know people are doing it. When a person turns 18, I think they deserve the right to drink, vote, & fight for their country. The age limit isn't stopping anyone anyway. If they are going to keep the age at 21, then our law enforcement needs to start enforcing the law because there are many people around the US that underage drink every day. People break the rules all the time. I think it would be a good and acceptable idea to change the drinking age the 18.
Current drug and marijuana laws are the same way. People are doing them every single day in the US. They should legalize it because in American and our society, people would rather do something they are told not to do then something that they are allowed to do. I think by legalizing these substances and making the age to do them 18, many people wont be so tempted to try them. People ages 16-20 are the age where they just want to try everything that they aren't supposed to and find out why they aren't supposed to do them. The age should be 18 for drugs and marijuana too.
Lastly, current alcohol, voting, and military laws should all be the same. The age should be 18 for all of them. 18 seems to be a common age that people are graduating high school and looking to further their futures by going to college. People who are 18 are being considered young adults. If someone can die for their country, they should defiantly be able to vote, and drink a beer. Voting makes them feel like their opinion actually counts. Fighting for their country makes them proud to be an American and thankful for their country. Drinking a beer would be the reward for all of their hard work. I say make everything 18 because why not?