"Highest earning people who didn't come from affluent backgrounds" is entirely consistent with "not many people".

None of the wealthy people I know had wealthy parents. Most of them had parents who didn't even have shoes for significant periods of time.

	▲	Xirdus a day ago \| parent [-]
		"Wealthy people" alone is also consistent with "not many people". There aren't that many rich people in general, musicians or otherwise.