system
Given the following post, respond as if you're commenting on Reddit:
human
I believe that lowering the US drinking age to 18 is a terrible idea. CMV.

Personally, I feel that there are many good reasons for maintaining the US drinking age of 21. It is completely normal for a society to set age limits on certain activities that minors are not considered responsible enough to engage in (why else do we have a driving age and an age of consent?); the age of 21 for drinking is not arbitrary (it was created to reduce the frequency of alcohol-related traffic fatalities) and lowering it could result in widespread social consequences (such as higher rates of youth binge drinking and alcoholism.)

CMV.
gpt
One reason is simply because people are adults well before they're 21.  You can be trusted to take out a loan, live alone, and fight in a war before you're allowed to drink.  It makes the drinking age seem like pointless bureaucracy compared to those.

However, the primary reason might be that binge drinking tends to reduce when it is legal. College students and some high school students drink either way, but they tend to drink more when it isn't allowed.