Your definition of basically spending what you make would end up with subsistence fortune 500 CEO's. People who don't directly farm are by definition not subsistence farmers.
PS: Yes, subsistence farmers can include minimal trade, but not support more than local governments as that would imply a significant surplus.
Re:Apple's cash hoard swells to $246B
by maxerickson on Sunday April 16, 2017 @08:19PM
(#14128403)
The more widely used definition of subsistence farming implies literal self sufficiency and living in a simple self constructed dwelling, not sending your children to college while slaves work in the fields or hiring local artisans to construct a grand estate (Monticello).
(There's always been some level of trade.)