I have a similar story to tell. My great grandfather was born into a wealthy family in Bangladesh, where they owned land that later became part of the city centre. For context the shit is so expensive now, 50m2 of empty land is worth the pound equivalent of £150000.
My grandad estimates his father owned more than 100 acres, so you do the math.
At the age of 12 or so my great grandads ENTIRE family (7 siblings plus parents) pass away from probably cholera or some disease at the time. (Grandad just says they all got diarrhea and died).
After the tragic death of his entire family, a family friend/c***,that worked for his family. Decide to "look after him" and his assets.
Fast forward to his late teens, great grandad decides he wants to sell some property , goes to the adopted father/ C*** asks for the deed, and surprise surprise he doesn't give it.
Eventually a nasty fight erupts, and at that time when disputes of the sort happened they were sorted by "village elders". The village elders were obviously bribed with a share of the property scammed from my great grandfather. And they are extremely biased when delivering justice and they help my grandad recover only about 12 acres. The rest they say they can't find the papers too or it was never his. In truth they all jointly sold most of the assets to people moving in from the rural areas, for a fraction of its true value.
My great grandad can't do anything about it as now there's so many people claiming his assets and property, and he is illeterate, young and alone.
He realises his illiteracy was the reason he's unable to do anything about it, so when he eventually has kids he makes sure to educate them.
My Grandad eventually becomes a lawyer and does attempt to recover some of the assets, The cases are still ongoing today, and is fought by my eldest uncle who too became a barrister. But honestly most of it is a lost cause as some of the property have passed hands so many times its just not worth the effort, or money required to recover them.
Not to mention the Bangladeshi judicial system that takes literally decades to pass judgement.
TLDR: Great grandfather had assets worth hundreds of millions in today's money. His family all pass away at the same time due to an illness, possible cholera. He gets adopted by a worker of his family, who steals all his property deeds. Great grandfather only manages to recover 1/10th of his assets.