I don't think this is accurate.
Gohan, without any real effort, is one of the most powerful beings on earth. He likes having powers and being a hero, insofar as he doesn't mind fighting regular humans doing crimes, but he doesn't have the hunger for self improvement that Goku and Vegeta have.
He's primarily a family man and an academic, he also went through a shitload of traumatic stuff pretty consistently from when he was four years old up until he was like what... twelve? So I could imagine that might make him less than fond of the idea of cultivating his own strength. There's basically nothing in his character that suggests he's very interested in training or improving his strength outside of when he is forced to because a world ending monster has shown up or the entire universe is at stake.
You reference the Cell Saga, dude was still a child. He didn't know what he wanted and his dad was intending for him to fight a killer super android bent on destroying all of humanity. He had to train because it was either that or the world ends. Based on everything he did in peacetime as an adult - going to school, getting a job, getting a wife and a kid and all that - that shows he doesn't really care to train and get stronger.
Vegeta and Goku blow off their families and other commitments to train and fight all the time because it's what they want to do. Gohan doesn't because he doesn't want to.