I have a background in Physics. As part of my Ph.D. studies in Granada into rotating black holes, I found myself doing a lot of work with computer simulations. I ended up getting deeper into the software side of things that way. Years later, I found that, in fact, physics and finance both utilize many similar high-performance computing techniques.
While I had experience with C, C++, and Fortran, what led me to Python was that it is so easy to start experimenting and doing things with the language. If you learn one piece of the programming language, you can connect it to the rest very easily. You can also expose some existing programs written in C, C++, and Fortran to Python as well. As the community participates in such a close feedback cycle with the language itself, it is constantly iterating.