The problem with the whole argument really is that when Rivers said "I can take 30 NBA guys and put them in the NFL," what NFL players interpreted from that was "Football is easy."
I didn't see Rivers' latest clapback, but James Jones fried him. And as pointed out, going with the "I made more money" argument is more of a copout as opposed to JJ's approach of "Perhaps you should have tried football because basketball wasn't your sport based on how your career went."
That said, it takes more skill to be a good basketball player than a good football player. That doesn't mean either status is easy to accomplish.