You don't have to be rich to have your needs met as a child such that you don't need to gobble up marshmallows as soon as you see them, unless you mean rich in

You don't have to be rich to have your needs met as a child such that you don't need to gobble up marshmallows as soon as you see them, unless you mean rich in the sense that the vast majority of the people in the US are rich compared to the global average. US middle class would be just fine in that regard.