My answer is that I believe mathematics is worth doing, and that math has improved the human experience immeasurably, in aesthetics, in ethics, and, yes, also in commerce and technology. Given this, I want to build the best tools possible for enabling our collective exploration of math.
There's a wonderful result from programming language theory called the Curry-Howard isomorphism that says there is a correspondence between all of math and all of programming. Every program is a proof, every theorem is a type https://en.wikipedia.org/wiki/Curry%E2%80%93Howard_correspon.... This means we can (and should) use computers as mathematical prostheses, to enable each of our human brain's ability to reason in this field.
And, via Curry-Howard, if we can make it easier to reason about math using computers, we coincidentally will make it easier to reason about computers using math. The two fields are, in essence, the same.
TL;DR "You may not be interested in mathematics, but mathematics is interested in you!"