I don’t think a definition of “earn” that excludes cases like that captures the generally understood meaning.
"Earning" is a subtle word with a variety of usages. One usage is limited to wages or return on labor or effort, and in that sense can refer to anything where a reward is due and proportionate to an effort, like a treat after a hard workout, buying a car after saving for years, or wages. Another usage focuses on profit. When AOC talks in the zone of this first sense, it should be understood that there is only an implied fair reward for sweat and tears, and that past a certain point it's really entirely unrelated to wages or effort.
How does he get the money to do that?
(And in California where the most profitable crops are perennial fruits and nuts, probably outright stealing water from the aquifer or state irrigation system.)