Well for starters there are many types of scientists that study galaxies.
Such as
Cosomosoligist
Astrophysicist
Theoretical Astrophysicist
Astronomer
The list goes on. The reason why is: There's a constant quest that we humans are on, the quest for knowledge and wanting to know more about things. Each day we make more discoveries. We want to know more about space, so that maybe one day we can live on another planet besides earth. For example they exploration of Mars, we sent a rover to Mars to collect samples and take pictures which led to the discovery of frozen water on the red planet. We currently have satellites in the orbits of other planets such as the one that takes pictures of Saturn. So you see, there are quests filled with insight, so that maybe one day we can explore deep outer space and find even more.