2. The first year could be a bit rough since you may be a borderline alcoholic.
You will take every opportunity to drink more than likely.
3. Your friends that aren't 21 can't go to the bar with you.
You may lose some friends, but you can also gain some at the bar.
4. Underage friends will always nag you about getting them alcohol.
Underage friends will get annoying.
5. Your parents will worry about you way more than before.
Now that you can drink your parents will worry if you are in trouble with the law or not.