I did choose to do some mathematics in Oxford for a few reasons. One, I love mathematics. Second, I love freedom, which you get in research. Third, I like being in a new country.
But this is not a final decision. I believe we do not have to be scared about making an ultimate choice about jobs, because nowadays people often change jobs and careers. At the end of my phd thesis (current position), I may completely change my focus, e.g. start my company in healthcare or work inside another company, if I desire to do so.
It’s fun working out how things work. I think intelligence (how does a brain work, what makes us smart, how do we get computers to do smart things) is one of the most enigmatic questions in science. So I’m glad I get to try to figure this out in my job.