PG himself is a good example. His equity stake in VC is very likely worth in the $1-10B range (YC didn't take outside capital, see footnotes: http://www.paulgraham.com/worked.html). But his ownership stake isn't transparent to Forbes.
I think a lot of VCs and real estate investors would fall in this category.
I think a lot of VCs and real estate investors would fall in this category.