Waaah trying to fix the environment is too hard.
It's easier to simply create a new home on a world without air, water, food or energy millions of miles away.
I know if human civilisation survives more than a million years here on earth then yeah eventually we'll have to leave, but leaving now??? So shitty.
Pulling a page from Three Body Problem / The Expanse, I'd argue that any civilization that exists outside Earth for multiple generations is functionally no longer human.