Colonizing other planets is way, way, way beyond our current abilities. It would be easier to colonize the ocean first, because at least that has water and a biosphere, or even Antarctica, because at least that has breathable air. Counting on flight to another planet is a bad idea: it’s infinitely harder than fixing things at home.
It’s just a matter of priorities. In order to build a spaceship and get it out of the atmosphere, you have to do a colossal amount of ecological damage, which is the last thing we can afford right now. Space ships are made with lots of lithium and cobalt and fun stuff like that.
I’m not saying forever, I’m saying that we’re in the ER for internal bleeding and you’re talking about doing an operation to fix our scoliosis.