I think it's the most common road to be a millionaire.
Microsoft - Bill Gates
Amazon - Jeff Bezos
Berkshire Hathaway - Warren Buffet
CDProjekt - Adam Kiciński, Marcin Iwiński (They started from absolute nothing, bazar stand with bootleg software)
TOYOTA - Akio Toyoda, branched out from family buisness in textile industry
Literally every single successful business made it's founder a fortune
We demonstrate that chance alone, combined with the deterministic effects of compounding returns, can lead to unlimited concentration of wealth, such that the percentage of all wealth owned by a few entrepreneurs eventually approaches 100%.
...note no skill required. Conversely, hustling won't get you there.
We show that a tax on large inherited fortunes, applied to a small portion of the most fortunate in the population, can efficiently arrest the concentration of wealth at intermediate levels.
So we don't even have to hit millionaire kids. Inheriting 5-10 million a head is fine, systemically speaking. And if you think that your kids are better off with more money I sincerely feel sorry for you.
This result is robust to inclusion of realities such as differing skill among entrepreneurs.
The key thing is that this paper looks at generational wealth accumulation. Even if families which consistently churn out stellar business people were in any way common (data says otherwise) that effect is still completely overwritten by already being ahead. As a billionaire kid, the extent of business skill you need to have to not lose everything is to hire people who have business skill and then slurp Caipirinhas on your yacht from your ample, ample dividends. And if you lose everything, well, you're losing it, on aggregate, to other billionaires, so wealth concentration still proceeds.