I don't read it as "destined to die", just that there is a non-trivial chance.
Mars… I want to be excited, but the more I think about it (and, bluntly, the more bad decisions Musk makes), the less I like the idea.
That said, Mars is sufficiently difficult in all the right ways that if we can make a self-sustaining colony there, the only way life on Earth will end is some kind of self-replicating swarm, either in the sense of an engineered pandemic (specifically an engineered one: a merely natural one we can probably defeat just like COVID) or a more sci-fi von Neumann swarm.
Mars has half our sunlight, it is colder than Antarctica, dryer than the Sahara, the air is thinner than the top of Everest, the soil is toxic, and we'd have to make any hydrocarbons from the air itself rather than digging them up.
Make a Mars colony work despite all of that, we'd easily survive a repeat of the asteroid-ending impact or nuclear winter here on Earth.
Yes; in several billion years, e.g. https://twitter.com/elonmusk/status/1482552643343904770
"There is a [100%] chance of all species extinction due to expansion of the sun, unless humanity makes life multiplanetary"
Do you disagree with this assessment? Either way, it is irrelevant to the claim that "billionaires [are] planning to move humanity to Mars in the near future"
You just invented the "several billion years" part. I absolutely, unequivocally believe the premise of the article we're discussing, that space-loving billionaires (like Elon Musk) and their acolytes believe that the earth is doomed to failure in the short term and that the only way for humanity to survive is to become multi-planetary. If you think Elon Musk is operating on several billion year time horizons, I have a spaceship to sell you.
As a first step, to prove Mars is liveable. As far as I can recall, he believes that we must be a multi-planetary species to survive which means Earth is destined to die.
Space is absolutely a “earth is doomed, we must leave” fantasy for Musk and his acolytes.