One way of reducing the chance of this is to not split the inheritance. Even a vast fortune is reduced to below self-sustaining levels in just a couple of generations.
In my family I had a polish/Lithuanian aristocracy ancestor that owned some towns and large landholdings (he had some sort of wood monopoly). In three generations the families were still wealthy and in the aristocracy but were living off their title more than their wealth.
Another friend of mine's family from India who's grandfather was some sort of king has been splitting their lands up each generation. They recently sold off the las of their lands that had the ancestral home, a couple of forts and temples, etc and now are all just living pretty mundane suburban lives.