The IRS reports that 18.7 million taxpayers paid self-employment taxes, and 7.4 million of them earned $50,000 or more annually.
8,214 of these self-employed raked in $10 million or more annually. (I presume this includes athletes, film stars, etc.)
4.8 million people reported positive rental income, of which 2.95 million reported earning $50,000 or more in rental income annually.
1.25 million taxpayers reported earning $50,000 or more in royalties annually. (7,585 reported earning $10 million or more in royalties–subtracting Steven King and a few musicians, who else earns these princely sums? I suspect most are patent royalties.)