What advantage is there to joining the military after highschool instead of going to college immediately after graduating?

Sgt Matt Medhat Joining the military first provides the following potential advantages:
1. A break from school
2. Time to mature and gain needed discipline
3. A better idea on what major to choose, along with a tight focus on obtaining that degree
4. The G.I. Bill

I think it's better to get a few years of experience in the private sector before entering military service. It gives you a real sense of the value that the military offers. The majority of kids who join the military come straight out of their parents houses, trading one parent for another. They don't realize they are starting a career. In my experience, people with prior service or prior civilian experience treat military service more as a profession with solid benefits and high school kids approach it as an adventure they are quickly disillusioned with.

However joining straight out of high school puts you way above your peers once you are a civilian. I left the Army at 21 and within less than a year I was assistant manager at a restaurant, a year later I was the shift lead at another restaurant. In the four years I spent after the military, I was constantly moved into leadership positions shortly after starting work at a new job because of the habits I picked up in the Army. Be on time. Do the job completely the first time. Fix problems before someone tells you to. Always say yes to a challenge.

Having been the kid that joins at 18 I realize kids really aren't capable of making life decisions at 18. Working with other prior service, I see that they approach the military as a career and a way to feed their families for the long term.

That completely depends on the individual and what their goals are in my opinion. We all get the same benefits no matter when we enlist. The only thing that makes a difference is the age you’ll be when you ETS or retire. High school students are looking at retiring at 38-40 rather than retiring at 50. Everyone has different reasons as to why they joined when they did. But the one measurable benefit that I can think of is time. How old do you want to be when you get out.

Sgt (Join to see) hit it dead on. Plus the military will provide TA to pay for your classes while you’re in. Get your Gen Ed classes out of the way first.

I did college straight out of high school. Had a year of the most fun I've ever had at the time, wasted a lot of money, made a lot of friends, got out of Connecticut....and finished year one with a very bad GPA due to zero discipline.
I joined the Army and now have 2 degrees with high GPAs for both in a field I know I'm good at and interests me (and is actually useful - sorry philosophy or early Armenian literature majors...), was able to give my GI Bill to my kids, and now get to stack some professional certs before I get out in a few years.

So it depends on the person. Some people can do it right after high school, others not so much.

While I fully intended to eventually go to college, I joined right out of high school to:
-Gain a marketable skill
-Mature
-Save money for college
-Travel
-Get a better idea of what I wanted to study in college
-Take a break from school

I have zero regrets for that decision.

Military: Training; Learning to Respect Yourself & Others, Love for America & The Constitution, Learning experiences from beyond your present age group. Wisdom.
College: Indoctrination; Selfishness, Hatred for all that is Wholesome, Hatred for America & The Constitution, Stupification.

Here's one. If there is even a remote chance the person may wish to retire, get in there ASAP. If that person wants to commission, there are ways subsequent to enlistment. Either way, the sooner you start, the sooner you finish. Then you have four years or so head start on your second career.

Not sure if it is an advantage or a disadvantage. I will say that from the start I saw a maturity difference in those who had experienced different things including college. This goes back to basic training. At sone point it tapers off and the lines become blurred as service progresses, but I would agree that life experience after school has its advantages upon service.

I went to college twice. Once right after high school, where I goofed off for two years and dropped out. I found the motivation and the discipline during my military service for college. My experience in the USAF was critical in getting me through two degrees.