What rewards though? Even with rapidly reusable rockets, I can't think of any resources on Mars which would be worth the cost of transporting back to Earth.

Maybe if asteroid mining becomes a viable business, Mars' shallower gravity well and higher orbit around the sun might give it a significant enough competitive advantage for bulk goods like fuel and water that may be needed in the asteroid belt. Still, that's a lot of "ifs" and "mights", for what is, even in the best-case scenario, very long-term venture.