How did DHH figure out his own metric for success?
Early on in life DHH realized the importance of intrinsic motivation. He wanted to do what he wanted to do.
In his third year in high school, for example, DHH realized he did not want to do math homework, so he stopped. He failed the class, but passed the year, and all the extra time allowed him to spend time playing video games and programming.
Survivorship bias aside, it's worked out pretty well for David.