Who told you demand for mathematicians is zero? There’s demand for
developing methods to solve the differential equations associated with
engineering needs (that’s my job, and it pays quite well), or how to
encrypt and decode information quickly, or how to use Bayesian
statistics to filter signals from noise, or how to take a bizarrely
large data set and make something intelligible out of it, etc.
The computer revolution has eliminated some math jobs, but created
many more. What I do with my math degrees didn’t exist in 1965. Of the
five fields listed here, I’m pretty sure four of them didn’t exist
before the computer revolution:
The job market for actuarial mathematicians and statisticians is also booming.
Did I say the demand for mathematicians are zero? No. It sounds what you’re doing is more of telling the computers what to do, how to get the signal from the noise, etc. But you’re not doing what the computer does, you are doing what the computer can’t really do. We still need people to tell computers what to do, what equations to use, etc.
Humans used do the computational things that computers do today. Computers are an example of automation.
The point is that a person should look for a job that is on the right side of automation, that the more automation that occurs, the more in demand their job will be as opposed to the opposite. Math skills alone won’t save someone from the Great Disruption.