There's a middle ground to what he's saying. Once you MASTER something that all your life has been in demand and incredibly lucrative, it becomes hard to believe that completely pivoting away from that knowledge is your best course of action. I believe in most cases these down turns seem temporarily, a short storm to weather with a small reduction in pay until things get going again (see Big 3 auto). Unfortunately things just keep spiraling downwards and by the time you realize it, it is too late.

Definitely such short sightedness and stubbornness can be associated with brilliance.