Earlier quoted context omitted.
"There should be some trillionaires walking around whose ancestors started saving in the Renaissance when modern banking began -- but there aren't." Carlisle Cullen. ;-) Anyway - this is a really good point, but I'll point out something else. Most of the wealthy would-be trillionaires whose fortunes got wiped out passed down another inheritance: their genes. Those same disasters that wipe out the savings of the rich…
Most of today's middle class is descended from the kings and nobility of the high middle ages. The peasantry just mostly died out, leaving no descendants. Source?
IIRC, the genealogical records (of most present-day Europeans and Americans being descended from the nobility) was presented as fact, but the causal link with the rise of the middle class was more tenuous.
I'll look again after I've gotten some actual work for $realjob done.