Why study calculus?
to be able to finally understand the importance of the ideas using Calculus!
what is Calculus?
the idea of things changing instantaneously!
Why study Physics at all?
Physics is a very interesting subject. You learn the aspects of the tiniest things that is the molecules, atoms, and electrons to the astronomical objects viz the Sun, the Galaxies etc under the same roof. It gets as fascinating as you delve more and more into it. There's, therefore, no single reason why shouldn't learn Physics. Physics is the answer to Nature!