Think about it this way. What if there was an uninhabited island out in the Pacific that was hard to get to. What makes it worth trying to get to? There isn't anything any more special there than here. In fact from all we've seen so far it's much less special. Same goes for Mars.
What is the value in being "multi-planetary?" I mean the idea that this is a hedge against some existential threat to humanity is silly. Mars is more hostile to human life TODAY than earth would be after a massive ELE asteroid - and the likelihood of an ELE asteroid is actually higher for Mars as it does not have a stable barrier atmosphere as good as Earth's - meteorites are more frequent as a result.
So best case scenario is that we have a group of people who put 75% of their time into just surviving because there is no atmosphere or biome to support them. On top of that these people have the same biological makeup - including cognitive limits, biases etc...as the rest of us on earth so even if they sorted everything out, tribalism and the rest of our hardwired heuristics would just make them behave like the rest of us.
The better approach is to start engineering our faults out using data to make us better, more resilient processors of information and discovery. Improve humanity and everything is easier.