You are ignoring the fact that you can join the military, go out and put your life on the line, yet, you can't have drink if you are between the ages of 17 and 21. As if somehow drinking alcohol requires more maturity, more understanding of the consequences of the choices made, than joining the military and putting your life on the line for this country, or even voting for that matter. But in all reality, drinking alcohol responsibly takes the least amount of maturity and understanding of the consequences, out of all three, partially because it has the least long term impact on the country, the world, and society in general for that matter. Yet, it's put on a platform as if it requires the most maturity, understanding of the consequences, and has the largest impact on this country, the world, and society in general., when it doesn't.