https://youtube.com/playlist?list=PLOLArO56vjuoeaIPzKQibBDbx...
At current interest rates, 11m in cash would yield 500k/yr in interest, so the top percentile in net worth is also top percentile in income, just from first principles. Of course, over the last two decades interest rates were hovering mostly around 0, so that math doesn't quite work out. People also have their wealth tied up in investments, some of which fared better (S&P 500), some of which did worse.
Note that it doesn't really matter if that net worth is in real estate or in equities, both REITs and the broad market indices have returned about 11% per annum over the last 20 years.
More than one in ten american households have net worth >1m.
Your last sentence is more concerned about social status than about wealth. Poor families can spend in high-status ways, and vice versa. Social status is weakly correlated with both income and wealth at best.
You can't just point to billionaires and see that they have almost 0 income. There are only a few thousand billionaires in the world, enough for each and every one to be individually tracked. They are not included in these statistics, because again there's only literally thousands of them. They're so far into the top percentile they don't touch the statistics here.
Wealth is also a much more durable measure than income, as very high incomes for many people don’t happen until mid or late career, or they may be one-offs (like from an IPO).
You can be in the top 1% of CA as eg a dual income family in South Bay both working lowish status roles like “senior/staff engineer” or “line manager”. That’s solidly upper middle class in practice until they accumulate wealth. There’s a world of difference between that and how a family with $15m in assets can live