There are several ways guys end up with extra field gear.

1. Anyone who uses the stuff regularly acquires two sets eventually. The field set and the inspection set. You don't buy it all at once, but slowly. The Clothing Sales store on Army posts sells some of the stuff, the rest you get at surplus stores off post or thru the mail/internet.

2. Joe goes AWOL. It is the rare case that all of Joe's stuff is turned in. He's gone, he's created a fair amount of paperwork plus PITA stuff for his buddies. So quite often, more often than not, people go shopping in his wall locker. If he didn't take it with, consider it gone. The cost of the items comes out of his paycheck, but poop on him, he's gone.

3. Paperwork snafus with supply. You are issued a widget. When you go to turn it in, the supply people say you were not issued one, no need to turn it in. Happens now and then.

4. You find lost stuff in the field. Amazing what people lose. Helmets, entire rucks, web gear, shovels, literally about anything has been found - except weapons. Lose a weapon, you and all your buddies stay in the weeds til you find it.

I still have a fair amount of stuff, most gotten legally, some found. Other stuff fell off the books I guess.

Generally, if you were issued an item, other than clothing in basic training, at some point you have to give it back.