[wakawaka28]

That's interesting. You should consider yourself lucky to have met Wolfram employees, as they are obviously vastly outnumbered by users of Mathematica.

I have not met any developers for either of these products but I know that SymPy has a huge list of contributors for a project of its size. See: https://github.com/sympy/sympy/blob/master/AUTHORS

You may not be hearing about SymPy users because SymPy is not a monolithic product. It is a library. If you know mathematicians big into using Python, they are probably aware of SymPy as it is the main attraction when it comes to symbolic computation in Python. They wouldn't necessarily spit out a bunch of libraries in the same breath as "I use Python."

[Affric]

I have been playing around with SymPy for the last couple of weeks because the CompSci department (not entirely uncontroversially) wants to become Python native for the students to make the courses more accessible. I have been looking into ways to incorporate SymPy and SageMath into my tutoring for the mathematics for comp sci students type units.

1261 is an impressive number of contributors. I am interested to see if I could round up some people to hack up some of these test failures.