I can see why since I am searching for jobs:
1. Juniors are no hired for C++ type roles. Employers want someone with 5+ years of experience, because just knowing the syntax is not enough. And training on the job is also not offered.
2. It pays shit in comparison.
3. Job positions are relatively scarce.
My actual niche is numerics (so writing numerical libraries and simulations), btw. I was really dismayed to see how shit the pay is.