The only thing I can guess is their brains have been fried by dramatized TV shows and movies where plot gives all the relevant information to explain all inconsistencies for a satisfying ending. Sometimes you're just a person in a cave looking at shadows, trying to find an explanation for everything with the little information you can gather in your life is a waste.
I've had a fantasy since I was young that I would live to see some start to building colonies on the moon or Mars. The older I get and realize how vast the distances are between the earth, the moon, Mars and anything else, I've realized that I don't think we'll ever really leave earth in anything more than to go into orbit around earth. People are very tied to the environment that we formed in and taking that with us to another planet will be prohibitively expensive and refreshing supplies to support that can largely only be done on earth.
Now I believe people won't make any permanent settlement outside of earth in my lifetime or ever.