I'll be the five millionth person to post this, but it is adorable.
I love this, and do completely believe the studies that say those that are better at delaying gratification do better over in life (relationships, money, pursuits, etc). However, I think the real failure here are that there are too many people in life who go through, and struggle for a little bit, eat it, and then think badly of themselves, or sorry they didn't get that second marshmallow. I bet that people who made a snap decision, ate it and never looked back would be far happier (and probably equal the success of the delayers) than the people who live in some miserable in-between state.