I said the same thing. My ex-husband was military (though not boot at all) and you could absolutely find this truck in the px parking lot. Probably driven by a 20 year old with a kid and a pregnant wife who goes shopping off base in his uniform solely so people will thank him for his service.
Boot is a derisive term, in this case it's referring to young inexperienced people fresh out of boot camp. The mindset refers to doing trashy and/or foolish things usually coupled with a strong sense of entitlement ("thank me for my service!").
Not sure who downvoted you, nothing wrong with asking questions to learn stuff.
Unless they are in the Army. Then they would rightfully call themselves a soldier. Soldier, Airman, Marine, Seaman, Guardian and Spacie. I guess not sure on the last one
I don't know, when he was older and it wasn't so stigmatized, my old man always had a "Vietnam service" bumper sticker on his trucks, but maybe that's different?