Honestly, I don't really get it either. As for tech billionaires dabbling in space, it comes down to what they expect to get out of it. In Musk's case he's ma

Honestly, I don't really get it either. As for tech billionaires dabbling in space, it comes down to what they expect to get out of it. In Musk's case he's managed to create a company that can launch payloads into orbit (and hopefully beyond one day) at what will hopefully be a fraction of today's launch costs if the promise of reusable first stages holds true. He's also managed to do this on a fraction of the budget that NASA seems to be spending on the SLS. Launching satellites is a commercial enterprise so hopefully self-sustaining. Must hopes to leverage this to one day colonize Mars. Well, good for him. Not sure what Bezos is up to but superficially it looks like a "me too" SpaceX. So why send things other than satellites into orbit or probes into deep space? That's really what it comes down. Some will point to the resources out there. This argument I just don't buy because the economics of any material on earth are many orders of magnitude cheaper than what resources from space could possibly cost. Take iron, for example. You're talking less than $100/ton. How could extraction from space possibly compete with that? Obviously accessible iron on earth is ultimately limited but even at $10,000/ton it'll drastically change human society. So what about colonization of other planets and moons? Well, first you need to ask why. To me, the only goal that makes sense is to ensure survival of humanity by creating a self-sustaining colony as anything built on the premise of requiring supply from Earth is ultimately just a vanity project. So what would it take to have a self-sustaining colony on another world? If you think about it, it's a lot and I'm not sure it's feasible with current technology. Also, where? Other worlds are pretty inhospitable. A lot are attracted to Mars but I'm not sure why. It essentially has no atmosphere (pressure is much closer to a vacuum than Earth's atmospheric pressure), which, incidentally, is one of the problems with the Martian (the movie at least; I haven't read the book). It lacks the Earth's protection against UV rays too. So what about interstellar travel? Sad as it sounds, I just don't think humans are built for it. We live too short a period. The distances are so vast that how would you ever construct a vessel large enough to make the trip and be self-sustaining or have enough supplies for thousands of years and then also propel it to the necessary speeds? The conclusion I come to is that there are simply too many of us here on Earth and this will resolve itself if we don't resolve it first.