The paradox of capitalism. Due to the positive feedback loop of capital it naturally gravitates towards a system where a single individual controls all of the capital, at which point the system has completely collapsed.
In practice it would have collapsed before that point, but for basically the same reason. None of the capital is where it needs to be to be useful. This is why you need stuff like progressive taxes, public works projects, and social programs on top of capitalism, to pull money out of the top and re-inject it at the bottom lest the system get too top heavy.
The article itself shows that each Disney generation has less money. The Kennedys are another example. Are the Rockefellers the richest people in America? The Vanderbilts? The Carnegies? The Morgans? The Astors? The Gettys? Nope to all.
The richest today are first generation - Gates, Bezos, Buffet, Musk, Case, etc.
In other words, the only way to stabilize capitalism is for those with the money-piles to spread it around just enough that those without don't try to take any extra.