Take the tax system and the state out of the picture. How does a mathematician convince his fellow citizens that they should fund their work? Newton didn’t have to do that, he had income from other sources and did most of his mathematical research as a hobby
because it could lead to something. the whole point of academic research is to uncover, as closely as possible, truths about how all of our myriad, hyper-complex systems work. not every truth uncovered is convertable to direct improvements on people's quality of life. like, how does understanding evolutionary biology matter to your average person? or finding the Higgs boson? should we just drop these research avenues because your average person won't benefit? or can we trust, based on historical precedence, that the slow march of research has created many of the luxuries we enjoy today?