I went from chemical engineering into data science, and I wonder this constantly. Everything about chemical engineering was much more difficult (at least what you would be expected to do in a typical job; exceptions apply). I really miss the hard sciences, but I also really do not want to take a 4x pay cut.
Also, I'm not sure about the supply and demand argument. The typical ask for a data scientist is much simpler than specialized ChemE knowledge; supply should have ramped up so quickly that comp would have fallen to typical engineering salaries long ago if that were the case.