[Eerie]

>Space hostile

Earth is hostile, too. A large part of human civilization is dedicated to making Earth more hospitable for humanity than it is in its natural state. We can do the same for space.

>Space empty

Only in a sense that a large container with a single fist-sized diamond is empty. It is empty on average. It contains an incredible amount of resources. Our solar system could easily house trillions of people (in O'Neill cylinders).

>for example in projects which research aging, cancer, overpopulation and disaster management in face of global warming

We already spend much more on these, than on space research.