You need to repeatedly solve multiple practical problems to internalize the knowledge. And you'll eventually need to do stuff that you don't really like at all.
Just a week ago mine found and devoured a pack of cookies that were meant for supper and then cried at supper that there weren't any cookies left, choking on a hated apple instead.
Guess he won't do it again in a week if there's another pack of cookies in the hand's reach? Guess again!
This was famously tested with the Stanford marshmallow experiment. A sizeable fraction of kids - preschool kids, no less - can in fact learn not to eat the marshmallow.
There are millions of people struggling to get on a diet, to quit smoking, to stop doom-scrolling their choice of social media. Most of them know very well how good it would be to stop doing bad things and start doing something good instead, and yet they don't.
Children are worse, overall, because life isn't as harsh for them as it is for adults. An alcoholic who can't quit drinking is risking his marriage, his career, on top of his health, and still pulls out a stashed flask and takes a sip. The worst that can happen to a child is that their parents will yell at him / her? That's a very weak deterrent against doing something that offers instant gratification.