Ceres is a good place for a lander and rover then. Might be some action there. Face it, Luna and Mars are boring, low-value real estate.
You can operate an unshielded nuke plant tethered some distance below your balloon habitat, no worries about leaks.
We don't know whether humans can survive for long at Lunar or Martian gravity. Zero-G we know is a problem. So, Venus might be the only other notionally habitable planet.
Flatlander wishful thinking is soon fatal out in the asteroid belt. You quickly learn better, or die.
It's either an amazing coincidence, or something about planet formation in our solar system that makes ~1G planets very likely.
But anything at or near Neptune receives very little light. There's a big gap between Mars and Jupiter (5.2au vs 1.5au), 10au to Saturn, and then a massive gap to Neptune (30au); anything habitable probably needs to be in the Mars-Venus band, fairly close to the sun.
It's worth noting that Ceres, and by proxy the vast material wealth of the Asteroid Belt, is only 25% further from Earth than Mars is. The biggest barrier is Ceres has 10% of the gravity of Mars or about 3% of the gravity of Earth. This isn't even close to enough for anything we would consider healthy living.
The act of finding out if there is life or not will probably raise survival chances on net, compared to never looking.
Much like passively looking for the monster in the dark room. The monster is either there or it is not, but if you see it you have better chances than if you don't (barring some specific contrived scenarios).