Lower the drinking age to 18

Mr. President, at the age of 18 we the people of this great country have the rights to many new things such as purchasing cigarettes, joining or getting drafted by the military, being able to sign contracts and being considered adults in a court of law and the eyes of society. If we can have all of these rights at the age of 18 then why can't we also be able to go to a store and purchase a drink? If we are old enough to put our lives on the line for our country then I think we should be able to go to the bar or store and have a drink as well. This will also go a long way with law enforcement focusing on more serious issues than underage possession and drinking