You are lucky just to be born in a nice country, I wont disagree but also mostly to get as far as billions takes more. A lucky start can be ruined by poor actions and the need to do nothing as they are already rich, I think mostly anyone who increases their wealth by that extent is likely created their own good luck by building on wealth with good actions.
Most people born into comfort lack the drive to build on good fortune and turn it into a massive amount. Its probably not a great coindence that Warren Buffet grew up in the great depression, he cites alot of influences but he must have seen alot of failures in his community before recognising a profitable firm.
Its also pretty cliche the rich child who wastes it all. A good risk taker understands when he is lucky and when to take the winnings off the table, an ungrateful person does not know the true worth to many things and loses alot of it like sand through the fingers :p
Yes, there is much that seems correct in what you write. Hard work, proper assessment of risks, personality (and other characteristics of many rich people, both that I know and have read about) all matter a lot. The converse is also true, that many who are comfortable at birth or young typically lack the drive to exceed "bigly".
Also, yes re your observation that a canny person who had some luck will "take some off the table" after a windfall. Yet, such a "canny" person may not go on to become a billionaire... (Taleb mentions dentists who do pretty well, but do not become really, really rich).
In my own case I was born into a rich country, and even to a reasonably well-off family. THAT was luck. Not very many people are lucky in that way.
