I'm not sure where I have been, but I have never seen this picture. I think I'm going to be sick.
Long ago, it was explained to me by a long-serving Marine what the duty of his Corps was, stripped of all the pretty words and happy thoughts of tradition and glory and such. It's true of all services, but his keeps it in mind more than some others. It's quite simple, really.
The duty of a Marine, and the purpose of their Corps, is to take a bullet that might otherwise go to an American civilian. That's all.
In that photo, you see an Army aviator who than now-deceased Marine would have immediately recognized as one of those of whom he was referring.
Next time you get the chance to thank one of those with that responsibility, you might take the time to do so. Most tend not to make a big deal of it, though at times, it can be a very big deal, indeed.