What historical period are you interested in? Because the aristocracy and monarchs of Europe are not doing great compared to 1915 and they’re doing a lot better than the nobility of any other continent. There have always been the ways to be rich, make it, take it or inherit it. Take it is no longer common in the developed world. For the super rich the top ten of the Forbes Billionaires List has three Waltons. The rest either made their own enormous fortune (6) or grew it out of all recognition.
It’s true there are outliers, and especially so at the very top, but the general trend is pretty strong. 80% of American millionaires are first-generation. Pointing at the 0.0001% says very little.