You know, in a sense we're already taking better care of what we have already. There's less poverty than ever before, as an example. I think the major concern right now for humanity is that of global warming. We're definitely not taking care of our planet right now, and long term it's probably the most important challenge we've ever encountered.
Being multi-planetary is linked to that - not as a plan B but imagine how much it will boost scientific research. Any kind of outside earth research may benefit Earth in the end.
Fighting poverty and hunger is of course noble efforts too (and they have worked). They can perfectly co-exist with space exploration.
Yes, research into space travel and what not might benefit Earth but not nearly as much as dumping all the money into researching Earth as a primary goal.
I got the sense that the comment I was responding to was saying that we might accidentally discover or invent useful things as a byproduct of space travel research.
For example, I believe memory foam was originally invented by NASA (or at least by researchers funded by NASA). Memory foam has improved the quality of life of many people including myself (I'm sitting on it right now!) but I don't believe that this is a good justification for researching space travel. Our money would be better spent by cutting out the middle man and directly researching things that will solve problems we know about on Earth.
That research will also have unforeseen applications much like research into space travel so we will still get those seemingly random benefits like Viagra being used for erectile dysfunction instead of whatever it was originally invented for.
I am simply not a believer that we should be investing money into things like putting humans on other planets. I don't believe that we need to spread out into the universe in case some kind of cosmic event destroys the Earth. I am perfectly okay with humanity going extinct in that case.
Sending rovers, satellites, and probes seems like a much better usage of money because they're a lot cheaper than trying to keep a human alive on Mars or any other planet. I am also okay with things like asteroid mining to get more resources to be used on Earth. That has a clear benefit.
I disagree with that point of view, on the basis that it seems humans don't seem to work that way. Historically, we tend to shy away from hard problems unless we have a compelling motivation to go there. So, for instance, your memory foam would probably never be discovered if the only research allowed was "how to make office chairs and beds more comfortable". There's plenty of options good enough for the market to lock down on them, and nobody would bother with spending lots of money on advanced materials science in vague hope it'll eventually result in a mattress good enough to compete on the market. So it turned out that NASA needed to go there for other reasons, and then the tech was there. Technology transfer is cheaper.
The argument boils down to the observation that you want to invest things that tend to generate lots of transferable technology. In the history of mankind, the usual "technology generator" was war. But we want to avoid that. Space exploration seems to be a very nice alternative (incidentally, itself spawned by war).
But in my comment, I was trying to argue for two other benefits of space. One is, a lot of money in space sector goes towards "directly researching things that will solve problems we know about on Earth". Satellites are vital tool improving our daily lives at all scales - from GNSS systems like GPS, through emergency response (beacons, satellite phones), to weather prediction, farmland management, climate monitoring, etc. Even the missions looking at other celestial bodies are important for Earth. We got our first concept of global warming problems through studying Venus. Monitoring space weather is important for communications down on Earth. Etc.
The second thing though, is the long-term potential space opens up once we cross the threshold of establishing a functioning economy outside of Earth's atmosphere. More resources, cleaner manufacturing letting us fix up the environmental damage down here. Opening up to practically unlimited livable space. Yes, it's far off, but you can't get from here to there without going through the current space tech phase.
Being multi-planetary is linked to that - not as a plan B but imagine how much it will boost scientific research. Any kind of outside earth research may benefit Earth in the end.
Fighting poverty and hunger is of course noble efforts too (and they have worked). They can perfectly co-exist with space exploration.