Except Starship is Elons vanity project with very few actual use cases.
It will also be necessary to launch the full size Starlink 2 satellites, which have been increasing competition in Internet access around the world, including in places that have had wars and natural disasters.
So, it has use cases.
No one needs to go to space, or probe the workings of the cosmos. Hell, 99.99% of all software ever developed is utterly pointless, yet it employs every last person on this site. Humanity does stuff because we think we can do cooler stuff than the people who came before us. And that's a perfectly noble goal, unto itself.