If you can even afford 20K you're in the top 10% of the US population. It's not a very big market, and even selling to that market is hard. Probably only 10% of that 10% will actually buy, and all of a sudden you're selling to 1%.

Selling to businesses is much easier, 99% of businesses can afford 200K if it replaces 3 x 70K humans.

Your napkin math only shows that the market is identical. There's about 35m businesses operating in the US. So by selling to 10% of those you sell the exact same number of robots...

Actually the high income households are becoming a greater and greater share of spending, referred to as the "K shaped" economy. For example, the top quintile of households accounts for about 40% of all consumer spending.

Most people finance vehicles that cost much more than 20K.

I'd gladly pay or finance a robot that could have dishes clean, laundry folded, and carpets vacuumed by the time our family got home.