This comment happens quite often, on HN and elsewhere. It's probably due to the decades it takes for space research invention to spread into consumer products

This comment happens quite often, on HN and elsewhere. It's probably due to the decades it takes for space research invention to spread into consumer products (and even then, people don't realize it). You can find the same kind of comments about theoretical physics being useless, for the same reason (but even worse). The amount of research done for putting people in space that end up "actually benefiting people" in tremendous. The current research for extreme water purification for the ISS alone is worth it, given the renewed importance of clean water now and in the next century(ies).