Sure, but it cannot support the expensive lifestyle some people chooses to have these days.
Expensive cars, big houses, aged wine, diamonds, many hi-tech material things etc
If you could get all of this just by mowing the lawn. everyone would focus on mowing-techniques.
A good friend of mine does large area lawn mowing - he was a millionaire by the time he was 40, now owns a huge semi and excavator, three $50000 John Deere Mowers, specialist tilt trailers, the works - employs half a dozen guys, owns a mansion up in the hills. Dude is doing real well, started when he was 20, and at 43 he is pretty set, and he still loves to be hands on, keeps him fit, but I would definitely call him a workaholic.