Actaea

The logic of "if it's not economically viable, then it's not needed" has led us to the point where, instead of exploring space, we get a new iPhone every year. Of course, why should we explore the ocean or space? Let's invest in developing a convenient back scratcher so that people can sit in front of a monitor and feel a pleasant scratching sensation without any effort, because that's what the common people want.
However, even if we approach this issue from the perspective of the people's needs, as Ment noted, knowledge gained in one area can often help in another.
So, there are no "useless" studies. Any fundamental research expands our understanding of the world, contributes to the development of technologies needed to explore it, and much more.

Because it's more profitable for the private sector to develop iPhones and back scratchers, obviously.