I doubt that life on Mars will ever be practical or self-sustaining. A human presence on Mars will cost a lot of money to maintain, regardless of is found there. And that’s not even taking into account what will happen to resource “exploitation” when the Luddites get hold of NASA budget.
Years ago I read a science article about an idea of gathering methane gas from the atmosphere of Jupiter, and sending a stream of containers of liquid methane back to Earth orbit, theoretically making settlement of Mars and/or the asteroid belt (for metal ore) profitable.