I'm in science, though not bioinformatics - I know people who are. Cant comment on the oversupply or not, but the positions I know about are primarily funded through short-term grants, which means low-ish pay and minimal job security. I know a few people who have gone the otherway, from bioinformatics to data science.

You might want to look at the career path of this guy:

http://scrippsscholars.ucsd.edu/gsugihara/biocv

Basically, math phd, stint at large finance house, and now works as a researcher essentially self-funding his work.