Tech billionaire Elon Musk, who runs Tesla and SpaceX, is trying to buy up all the houses in Boca Chica, Tex.—a tiny community of just a few dozen people—so he can use the area to launch his Mars spaceship. He says he might have people on their way to the Red Planet within a decade.

Amazon CEO Jeff Bezos also has a spaceflight company, Blue Origin, and he sees the project as a stepping-stone to a future of space colonies. Bezos envisions that one day a trillion or more humans could be living somewhere else in the solar system, leaving Earth behind as a sort of park. The late Microsoft co-founder Paul Allen founded Stratolaunch, which similarly had space travel in its sights. (There's also Richard Branson's Virgin Galactic; he's not from the tech industry, but still....) These men aren't necessarily focused exclusively on space, but why do they put billions toward launching humans out there? One reason is that Earth is threatened with climate change and nuclear war; space is a kind of plan B. But a crewed flight to Mars is full of perils—most notably the fact that we don't currently have a way of protecting humans from the adverse effects of months and months of deep-space radiation. And once we get there, the planet's lack of a significant magnetic field or atmosphere means the threat will still be substantial. It's also not clear whether proposed plans for hauling the tons of supplies needed to make life there even barely possible could work as well as envisioned (or at all).

Still, what's wrong with dreaming, right? In one sense, nothing. But in another, it matters how people with a lot of money dream. Bezos, Allen and Musk all have talked about their love of science fiction as part of their inspiration for investing in space. Bezos spent his summers reading authors such as Isaac Asimov and Robert A. Heinlein. Allen so loved his boyhood science-fiction collection that when he discovered that his mother had sold his books, he had the entire collection re-created.

As a former science-fiction geek myself, I can only sympathize. At its best, though, science fiction is a brilliant vehicle for exploring not the far future or the scientifically implausible but the interactions among science, technology and society. The what-if scenarios it poses can allow us to understand our own societies better, and sometimes that's best done by dispensing with scientific plausibility. For example, Ursula K. Le Guin's brilliant book The Left Hand of Darkness imagines an envoy from Terra (our Earth) to Gethen, a planet without fixed boundaries between genders. Through the hero's encounter with an “ambisexual” species, we end up interrogating our own cultural norms around masculinity and femininity—groundbreaking for a book published in 1969.

Science fiction is sometimes denigrated as escapist literature, but the best examples of it are exactly the opposite. For me, it's not the scientifically implausible part of science fiction that is most interesting. It's what the expanded imagination allows us to discover about ourselves and our societies—and then to make them better.

Science and art have always been somewhat funded through the eccentric interests of the wealthy, and the combination has always been a mixed bag. One thing about being a billionaire is that it's probably not hard to find people who will encourage you to spend money chasing space operas that either will not happen because of scientific constraints or will end up in disaster.

But more important, tech billionaires can shape our lives today, through how their companies operate, by repaying their obligations to society through taxes on their enormous wealth (at the moment, fairly little), and through their investments in solving the problems that threaten us. Doing that requires imagination. It's just not the kind depicted on the covers of science-fiction books I, too, read as a child; it's the kind that takes us to expanded universes only to have us think harder about how to understand the one inhabitable place for us in this vast universe—our fragile, pale blue dot—and make it a better place to live.