Actually, the biggest threat to space exploration is actually the unwillingness of people to do it.
Even with current technology, we'd have a shot at a Mars landing now, if we focused our resources on it. However, I'm not asking for that. We can take our time on that, but you don't have to shut down one thing to make the other thing happen.
As for afterlife, I have other plans for the afterlife than floating in space. This isn't about that.
There are some people out there, apparently you included, who think that throwing all the money at a problem will fix it, and it can never be fixed without all the money. This is not at all true. We can add NASA's entire budget to feeding the hungry, and we'll get the same result. You know why? Because the reason that the billions we're already throwing at aid programs isn't working is politics and corruption. Politics and corruption will eat up *any* amount you send at it.
Aid packages that have been sent to war zones and areas impoverished by government failures are either regularly left to rot on the docks or are taken by the local powers that be and used to maintain their control over the populations.
As for health care, everyone is going to die eventually, as you seem to understand with your afterlife comment. It is as much as a black hole as anything else. You're never going to attain immortality for your population, but if somehow you managed to, you'd better have somewhere to put them.
As for space, yeah, there are vast empty stretches and very inhospitable conditions. Despite that, it is believed that the entire galaxy could be explored in less than 5 million years by robotic exploration. That's because space is big, really big, but there are places to go between here and infinity.
There's more to life than sitting around trying to feed yourself. There are places where we can still adventure and space is a big one. More than anything, as a species and a culture we need the challenge of space exploration almost as much as we need to remain fed. Looking up keeps us from navel gazing and helps us avoid fighting over petty things.