I remember in the distant past a video about a ‘study’ of kids who are given a marshmallow, and they are left alone with it after being told that if they don’t eat it, they can have more later - but if they eat it now, that’s all they get.

And later I heard that they looked into the kids that had ‘poor impulse control’ because they ate the one marshmallow … and these kids apparently had grown up in an environment where promises were often broken.