My grandparents were accountants and set up all their grandchildren with 5-figure trust funds by the time the last of them were born. After decades of growth, each one would amount to well over the gross salary for a typical professional. If I wanted to live on about $500 a month (I've lived for a while on substantially less), I would never have to work a job again.

Owning several thousand rental properties is a few orders of magnitude wealthier than this.

If the profit from a rental unit^[Using relative terms so as to be broadly applicable and not have to delve into currency specifics.] is about 1/20 of what it takes to live comfortably^[We all know that it's way more than that, but I'm using a conservative estimate to steelman this.], 2000 rental units are enough to support 100 people living comfortably, or 10 people living quite lavishly.

"The opulence of the few presupposes the indigence of the many" -some guy