Starting in the late 1960s and early 1970s, Walter Mischel began conducting a series of studies similar to the video. He was interested in the idea of delayed gratification. Years later he decided to follow up with the original people in his study. He found that when the people in the study who were able to delay gratification became teenagers, they were more successful in school, received higher test scores on the SAT, and were better able to cope with stress and frustration. He’s followed them even further into adulthood and the differences continue. The children in the original studies that could not delay gratification as pre-schoolers, were more likely to have problems as adults, including drug abuse.

https://www.blog.theteamw.com/2009/12/01/100-things-you-should-know-about-people-16-the-ability-to-delay-gratification-or-not-starts-young/