The size of a family grows exponentially with generation. Assuming a young couple. In 3 generations (~70 years) the family size would have become close to 10x.

The size of a family grows exponentially with generation. Assuming a young couple. In 3 generations (~70 years) the family size would have become close to 10x. More often than not, wealth is divided among extended families. So, to maintain per-capita wealth, the initial pool would need to grow at a matching rate by 10x in 70 years -- which is an annual growth of roughly 3-4% (in real value, i.e. over-and-above inflation). Otherwise, wealth will simply be diluted exponentially, apart from getting consumed/expended. (Unless at every step you manage to keep marrying rich) If you start with a large amount of wealth, achieving such a growth rate (3-4% per year, in real value) is no mean feat. 1. For starters, one cannot depend on "employment" which has a relatively small return. You need to find a way of earning money on your capital. 2. The political and societal conditions might not be conducive. The person(s) in the zeroth generation might have been lucky in many ways. This relates to the idea raised in the OP above. 3. People growing up in wealth might not have the skills, or the luck. 4. Or they might not have the desire. They might prefer to move higher along Maslow's hierarchy once the lower level needs are met. To quote John Adams: "I must study Politicks and War that my sons may have liberty to study Mathematicks and Philosophy. My sons ought to study mathematicks and philosophy, geography, natural history, naval architecture, navigation, commerce, and agriculture, in order to give their children a right to study painting, poetry, musick, architecture, statuary, tapestry, and porcelaine."