18 vs. 21

Just a random topic i felt would get a lot of feedback.

Does anyone else find it odd that (in the US) you're considered an adult at 18; can legally move out/get kicked out, fill out all your own government paperwork, enlist in the military, open up bank accounts, take out loans, get married, vote for the future of your country, etc. .. but can't drink legally until you're 21? Lol

Now It's not something im so overly concerned about, i get as a country we have bigger problems, but I've just always found it odd lol anyone else?