I have seen a lot of rich kids that went as poor as a church mouse when their dad kicked the bucket. And some rich people that lost all their wealth due to market melt down. Most of the kids that were lectured by rich parents, don't practice what their parents thought them. Instead the poor ones who studied the materials of wealthy men; books, audio tapes, and go ahead to practice it find themselves ahead of their rich peers. Both the Rich and poor must work hard to be financially stable else they'll fail and lose out all they've got. Don't forget that health is wealth same way knowledge is equated to power. Sickness can drain a generational wealth to bankruptcy and debt.
You are right. People get poorer because they don't invest time on things that works; yields money. They tend to fail because others failed. Have you thought about people who targeted to make 50k a year, fortunately they made 100k a year and they weren't able to control the money because it's more than their expectations. What actually causes such behavior? Whatever the answer is, contributes to the high number of poverty everywhere in the world.