Can we conclude that such are individual destiny?
No, I don't believe in deterministic outcomes. If you work for 20 years and are still poor, you've likely made willful decisions that have kept you secured to the low income group.
Educate yourself with a diverse and marketable skillset, earn more than you spend, and set aside funds for investment early to allow for accrual over 20 years plus and your chance of being impoverished is virtually zero.
Poor people are still poor because of their mindset, if they will change their mindset and will think like a rich , they will also become rich after 2 to 3 years. If a person is doing
a job and financial literate, he can can become rich by investing in other business, by investing in Bitcoin or by investing in property or gold. Does not matter how much you earn. The matter is what is your monthly income. And are your expenses. When your expenses will be greater than your income, you will be in burden and you will be poor because in way you cannot get financial freedom. Also, asset and liabilities ratio also depends a lot. Most poor people think that their living house is an asset and should be good investment but in reality living house is a liability because it takes out money from our pocket. If someone wants to become rich, he should know all these fact because without understanding these fact he cannot become rich. Poor people work for money and for rich people money work. That is a big difference between rich people and poor people.