Over a longer time period, it would be observed that some of the rich eventually became poor, as a consequence of either poor decision-making or accidental circumstances (illness, natural disaster). In the same period, some of the formerly poor would become rich, because of good decision-making or good fortune.
That is always true, everywhere, just as it is always true that some will handle money wisely and some will not. The wise can become ignorant or have bad fortune and the ignorant can learn but generally speaking the wise remain wise and the ignorant remain ignorant.