The top mosty likely existential threats, including "what the universe could do to Earth" would leave it more habitable than Mars.
If "lifeboat for species" is the goal, then going to Mars is a solution in that direction but not a particularly good one - building an underground colony in Antarctica or a self-sustainable isolated underwater colony would achieve the goal better, be reachable quicker, and at a lower cost. However, 'lifeboat for species' right now is not an explicit end goal for anyone who would be capable to fund that.
It's very hard to imagine what we could do to Earth so that it becomes even less hospitable than mars.