It’s good when children grow up in security, without hunger or want; it’s bad when they grow up lacking gratitude.
When we look at this particular idea and apply it to generations we can begin to understand how, as each generation in a free society becomes materially better off it also becomes lazier and more selfish. In parts of the world where we see high poverty rates we can also see closer family structures and greater levels of gratitude. To counter the risk of character decline when a family is materially well off requires strong parental discipline. Children need a work ethic more than they need the latest shiny toy.
I was able to witness your theory in person first hand when I was on Church work camps in Mexico and Africa. Great observation.