Photography is a tough job. It's wracked with internal politics, people playing favourites and in general just a lot of work. Honestly, it's easier to get $250k in VC funding than to sell your first break out photo essay (even if it's brilliant). I'm not an actor, nor a novelist, but I imagine it's a lot like trying to get your first big role or your novel to even get read by an editor. It's a painful grind on a day to day endless cycle of rejection.
Let's not even start with the fact that news staff jobs are basically non-existent, so most of these photographers are going into war zones with no backup support, no insurance provided for them, and it's all done on spec, so it's literally laying their life on the line with, if you're lucky, $3k for two weeks worth of getting shot it. We could then get into the mental health aspect of working for very little, very hard, while also facing the very real prospect of death every day (remember, probably no insurance for therapy or zoloft back stateside).
This is just for war photographers. For your day-to-day working photojournalist it's actually worse for pay and you have to be on call 24/7 or else they'll move on to the next guy/girl and you're out of rotation. Good luck going on holiday.