I think it's a heavy metal thing... I've been to a handful of Hip-Hop shows, I remember the last one I was we were up at the front and some dude started doing that. Everyone was like WTH? And security kicked him out.
Meh... I remember rap/hip-hop having a mosh/pit whatever phase in the 90's (see
ONXY "Slam!")when I was a young'un... No idea if it still goes on, im too old now for that sort of nonsense (fun

).
Never having gone to a Metal concert or been in a metal-mosh pit myself, I can't help but wonder if a couple on a date might be treating going close to the pit as an exciting, thrill seeking, bonding-to-induce-sexytime-feelings experience. Is that something that happens?
B/c I can imagine a situation where you might want to impress your date (especially someone new to the experience) by saying "Look honey, see that pit? Looks scary right? Let's get closer, it'll be exciting! Don't worry I'll protect you! (thus making you feel safe, building trust and proving my worth as a companion/sex partner). In some ways I can imagine this being the perfect semi-controlled environment to experience some pseudo-danger together without too much risk of death or maiming.
I will admit that it seems like guys are more likely to try to impress dates in this way than girls, but I could be wrong... again I have never been to a metal concert... but if it is more likely that guys do this, then the OP seems on point in raising the issue of whether guys (trying to impress their dates with their machismo protection contrivance) are putting others at risk for their own purposes.
FTR, to me the whole exercise seems kinda like a clear case of "at your own risk" activity for everyone at or near the "pit."