This is all true. If this was the only factor though, there wouldn’t be any social mobility at all, certainly not in any downwards direction but also not upwards. The richest 50 people in the world would have the top 100-200 children in the world in terms of opportunities and the billionaires list wouldn’t have a single surname that wasn’t represented in the 19th century elite. This is clearly not the case, though.

The net result is that the process of getting rich is often a multigenerational effort where each generation does everything they can to give their own children more opportunities than they ever had. And if you talk to the people who do that, they’re often motivated by the experience of being poor and hungry and deprived and being willing to do whatever it takes to give their own kids a better chance. Conversely, if you’re born rich, sometimes you’re complacent and entitled and probably spoiled and lazy. There’s a proverb about how many generations it takes to go from rags to riches and back to rags.

Without causing this to become an argument of semantics, generally speaking, the US has higher class mobility than the rest of the world. No, it is not commonplace for someone born in abject poverty to become fabulously wealthy, it's not commonplace for anyone to become fabulously wealthy. That said, it is rather common for folks to come to the US in pretty close to abject poverty and grow to sustain a middle class lifestyle, something which is nearly impossible in most of the rest of the world. Is someone with a middle class lifestyle in the US "rich"? I guess it depends on your outlook, and this is where semantics plays a part. Mobility is not entirely caused by intelligence or hard work, but they definitely play a part.

You are correct that the best way to become rich is to be born into a rich family and inherit the wealth (or the opportunities that create wealth). But it is simply false to state that this is the only way, or even the predominate way, in which people become rich in democratic free markets. There are a LOT of small business owners in the US that, are at least on paper, millionaires, and most of these people were not born into rich families. Through my life I've known many wealthy people, and only a handful were born into generational wealth, the majority grew their wealth during economic booms and worked to entrench it so they could survive busts, most by starting a small business in a high-value niche. By global and national standards, many people who are simply professionals and not even business owners, are rich or wealthy, just by being smart with their money. If you own a home and are working a job that pays six figures for your entire career and invest well, you will retire a millionaire without much difficulty, which definitely puts you in the upper quintile in the US.

This fatalistic, defeatist, and frankly infantile attitude from some people that acts as if wealth is only ever granted by random chance and at birth is utterly ridiculous, doesn't help anyone, and is factually incorrect from every angle. Your comment clearly illustrates an understanding of this, but you seem bent on defending the thrust of the comment I was replying to from the other poster.

Rousseau said, "Money is the seed of money." We can guess at the myriad of reasons but we don't have to wonder if it's true. I'm sure you've read this but if not, it's fascinating:

The Wealthy in Florence Today Are the Same Families as 600 Years Ago

https://www.wsj.com/articles/the-wealthy-in-florence-today-a...