Setting aside all the intangible benefits such as answering why we are here and providing inspiration to generations there are tons of short and long term benefits.

In the short/medium term, research is so much about solving problems and your solutions having unexpected applications in other areas. A lot of our minituarization in tech happened because we needed things smaller and lighter to lift into space, think things like your smart phone camera or laptops. Also things like cordless tools and even memory foam were originally developed for their application in space travel.

In the long term, let's take a look back, what if we had the same stance when we looked at the ocean, and thought why its even necessary to figure out how to navigate the waters. For our species to propagate or even survive, we need to expand. Right now we are one decently sized asteroid from extinction, but if one day we figured out how to expand to multiple worlds, then we become a heck of a lot of more resilient.