Learning stuff. That's the only thing that we do better than any other animals. If we aren't doing that, might as well pack it all in, allow ourselves to fade as a species, and leave the Earth to the goats.
The first US landing on Mars was in 1976. Since that time, there have been a whopping 9 successful landing missions: Viking 1 & Viking 2 in 1976, Pathfinder in 1997, Spirit and Opportunity in 2004, Phoenix in 2008, Curiosity in 2012, Insight in 2018, and Perseverance in 2021.
Only 5 of these could be called "rovers". One rover (Pathfinder's Sojourner) traveled a total of about 100 meters. Spirit drove about 4.8 miles. Opportunity covered 28 miles. Curiosity has covered 24 miles, and is still going.
So, all in all, we've seen only tiny portions of the planet up close. There's tons more left to learn. And we keep creating better and better instruments.