For sure, but until we do, it's reasonable to ridicule it.
(And I'm saying that as an optimist because I want the billionaires to develop that tech: the ability to fully terraform Mars into a self-sustained world is necessarily also sufficient to handle any imaginable damage to Earth up to and including a surprise impact with a moon-sized rock that excavates the crust and mantle everywhere to a depth of a few thousand km, meaning that things like greenhouse gases and biodiversity would become as easy to fix in that future as a single broken window is today; even just the bare minimum of a single self-sustained domed city on Mars means most environmental issues have to be "solved").
(And I'm saying that as an optimist because I want the billionaires to develop that tech: the ability to fully terraform Mars into a self-sustained world is necessarily also sufficient to handle any imaginable damage to Earth up to and including a surprise impact with a moon-sized rock that excavates the crust and mantle everywhere to a depth of a few thousand km, meaning that things like greenhouse gases and biodiversity would become as easy to fix in that future as a single broken window is today; even just the bare minimum of a single self-sustained domed city on Mars means most environmental issues have to be "solved").