I don't think I've mentioned this before, but I'm a former Girl Guide. I went all the way through the program from Brownies to Pathfinders—"Sparks", for girls who are about five years old, wasn't introduced until I was about seven or eight—and I earned my Canada Cord in 1999. I was a little bit older than the average for it, but I joined Brownies about a year later than most girls, and I spent an extra year in Pathfinders because paying proper attention to my schoolwork hadn't left me enough time to accomplish everything I wanted to before leaving Guiding.
Now that you've got the background, you may well be asking: what does all of this have to do with marshmallows?
Well, once every year in Brownies and Guides, we played a game. We were all seated in a circle in an order assigned by the leaders; once that was done, the leaders would read out stories of good fortune, bad fortune, or anywhere in between. Each story would end with either "take [x] treats" or "take no treats" and occasionally "take [x] treats, but give half to the person with the most treats." The treats they used were marshmallows. And at the end of the game, we'd always talk about how it felt to have a lot of treats or none at all. Afterward, the girls who had a lot of treats were encouraged to share with those who didn't have any, or didn't have as many.
This was always an interesting social experiment in itself; the girls who had been given a lot of treats were always reluctant to share with those who had few or none because they viewed the treats as rightfully theirs.
As for me, I was one of the ones who was, year after year, seated in a position where my stories gave me no treats. This made a major impact on me, and I noticed the sudden greed of the girls who had been given a lot; even when they did share, they were usually inclined to only share with their close friends. I also noticed that the leaders must have had specific outcomes in mind for each of us, because usually we were allowed to sit wherever we wanted while in our circle—assigned seating would only have happened if they wanted you to have a specific experience. But it wasn't until years later that I realized: that's a hell of a lot like being part of a system that's set up ostensibly to help you, but subtlely (or not-so-subtlely) sets you up to fail.
And it's an interesting microcosm. The selfishness shown by the girls with lots of marshmallows looks an awful lot like the selfishness of those who hoard wealth and whose lives are drenched in privilege. But I also remember one other thing that, in retrospect, is every bit as interesting: being given treats when you'd just been denied them by the rules of the game also felt embarrassing. It's like the difference between a handout and a hand up. And while a lack of marshmallows is rarely a problem, being shown only a grudging amount of compassion, or compassion on terms which allow the giver to say "look at me, I'm such a fantastic person," is not just embarrassing—it can be emotionally draining, and in the end, the person who is the recipient doesn't necessarily get what they actually need—just what the person with more resources is willing to give.
Take it from me: it never feels good to be given crumbs, and to be expected to be overwhelmingly grateful for them, when other people get to feast.
(For anyone who's interested: a variation of the marshmallow game can be found in this .pdf document.)