The prime predictor of financial success in life isn't merit or hard work, but still is what it always was: who your parents are.
Are the rich in the US more likely to have discovered, innovated, or created value, when compared to the rich in Russia? Or more despotic governments? I think so.
Does this mean the US is the platonic ideal of meritocracy? Probably not, rent-seeking does exist. Some rich have provided negative-value to the US.
I mean, when you drill deep enough, the entire concept of merit is pretty messy. There really isn't a clean way to isolate merit as a pure, elegant, factor. We are very much the product of our parents.
(There is another perspective as well, that success in part due to your parents isn't even bad or non-meritocratic. The concept of the family business, or an investment in the success of a lineage, was the typical way of viewing the world up until recently. A parent working hard in order to provide their child a higher chance of success doesn't have to violate meritocracy -- although this is a point of values).