I joined the Marines in 1973 at 17 and it was one of the best things I ever did in my life. They took a boy and turned him into a man.
The training I got is something I still revert to even these 30+ years later. It is not brain washing, it is the intense sub-conscience training that was instilled in me. I am in a leadership position at my job. I am proud of my service and the things I did when I was in the Marines. I never killed anyone but, I could, even to this day.
I was glad to hear that the Marines have returned to the training like we had during the Viet Nam Era. That is the kind of training that is necessary. It will help to separate out those that are potentially not able to handle the stresses of combat. PTSD is real but, unfortunately there are some that abuse the system and make false claims which sheds a bad light on the entire illness.

Also, proper mental screening before sending troops off to combat is necessary. More intense screening before allowing them to join is needed too.

I work with and around Veterans all day. Most are truly in need but, there is a large minority that game the system which makes it hard for those that are truly in need of help.