I get that part but what tangible benefits will I/humanity see from it? Or is it more of a case of gaining more knowledge about how the Universe works in the hope that that knowledge combined with other knowledge may lead to something eventually?
And not everything is done as a benefit/loss game - I would personally invest significant time and money into finding out how the universe came about, even if such knowledge doesn't do anything for starving children in Nigeria. However, the beauty of it is that you on the other hand can go and spend YOUR time and YOUR money on whatever YOU please. As for public spending - if you don't like it, go and vote.
However, your children, and their children, and so on will likely see benefits from it. The future is impossible to predict, however, so nobody can say what they will be. The principal benefit of missions like this is the new knowledge they generate. That knowledge is then the intellectual heritage of humanity for eternity, and can be used for any number of inventions, benefits, and future discoveries.
You are thinking too small. Even if somehow nothing ever comes of this mission, this is the sort of thing that humanity does not because it has survival value, but because it gives value to survival.