500K+ is enough to survive comfortably after you work for a moderate stint. Or to afford a significant capital investment like a small property, or to work for yourself on your pipe dream for awhile.

If people saw a path to long-term financial security which would enable them to drop the shackles of full-time employment before retirement age, of course they would flock to a profession. But they don't; they see a comfortable wage that could potentially evaporate if there is a bubble, or the field moves rapidly, or there will be a glut of people trying something similar by the time they finish retraining.

It's a risk:reward decision, and the risk is far from 0. So how much is that theoretical 100K really worth to someone looking at a very large investment to learn a new skill?