"Are they underpaid or are the others spectacularly overpaid ..... or both?"

Yes. Both. Jockeys daily risk their lives and well-being for peanuts. Ballers risk sitting out a year while getting paid handsomely to rehab torn tendons.

But what sort of cash do their employers generate from their businesses? By that measure, ballers are probably underpaid, while the jocks are lucky for the peanuts.