Space is the eventuality of mankind. We can't neglect it. But it is right that we can't just discard planet earth and expect we will fare any better up there where materials are scarce and every law of nature is trying to kill you.
Its a fantasy the rich use to distract from improving conditions and humanity's behavior (particularly their own) here geographically + economically and now temporally.
If we can find the money and political will to terraform something like Mars, we should probably take .01% of that budget and turn the earth into paradise first.