Because it’s simple to grasp, easy to write, well-suited to the fields in which it is used (things like first-class multidimensional arrays, native complex numb

Because it’s simple to grasp, easy to write, well-suited to the fields in which it is used (things like first-class multidimensional arrays, native complex numbers, good auto-vectorisers, things like OpenMP…), and quite efficient. It is quite interoperable (it’s easy to use anything that is callable from C). It’s easy to archive some code and be sure that it’ll run in the foreseeable future. Overall, it is a nice language to work with if you’re doing scientific computing. The rest of the world does not care much about its strengths.