Not really, because we can take our time and plan and research and try and fail how to operate in mars hellscape level B.
When earth hellscape level A happens there will be no more time left to prepare.
Yup. And unlike on Earth, getting self-sustained settlements on Mars to work is actually within the motivations of at least some people with resources - which makes it a perfect way to develop technologies we need on Earth to hedge against catastrophes, but that we otherwise won't develop because it's not immediately profitable.
This alone is a reason to support the space program. The excitement and curiosity it taps into gives us an opportunity to fund science and technologies we need longer-term, that are otherwise unfundable.
A Martian society would survive by virtue of already being equipped to operate in a hellscape.