Without question, most families with six figure incomes could afford to spend $10 or $20K for a full-time employee of some type. I would guess that few decide to make such an expenditure, since they have better uses for their money.
Being rich means having the wherewithal to be able to make such expenditures without compromising on more desirable items.
Even so, far fewer than 20% of the population live in six-figure income families.
As for the middle class, most data reflect it to be shrinking, in the sense that income and wealth are increasingly unequal. That is not inconsistent with the statement that the number of people in the top x percent are increasing and perhaps becoming more ubiquitous and annoying all the time.