As an astronomer, I’m always hit with the “what’s the practical use of this” question. My general response is, “Well, what’s the practical use of the Sistine Chapel?” Life can’t all be about practical down to earth things. There has to be beauty and art and discovery and awe. All our practicality has to be oriented toward something beyond ourselves.
But there’s also this. Sometimes just monkeying around with science produces unexpected insight. So research into jellyfish produces an AIDS treatment; screwing around with microwaves produces lasers and going to the moon produces remote sensors to monitor patients.
It’s a big universe out there and we’ve uncovered only a tiny fraction of its secrets. We should keep digging because we never know what’s going to turn up.