[smsm42]

At least in the US, old money effects are not as huge as one would think. Of course, everybody knows about Donald Trump, and maybe other people with inherited wealth, but there's also the survivorship effect - if somebody had rich parents and spent all the wealth how likely you to read about him in the national press? Nobody cares about those.

Moving onto more statistical approach, this one: https://www.fa-mag.com/news/most-millionaires-self-made--stu... says only 8% of millionaires inherited their wealth. For billionaires, according to this: https://www.entrepreneur.com/article/269593 18% got a jump-start (maybe parents were mere millionaires, but the child became a billionaire), and 62% are self-made. So inheritance effects exist, but maybe they are not that huge? At least, clearly, not a majority.

Of course, not everybody starts in the same place. But human behavior and motivations are similar, and thus you can reason about them despite the differences.