If you have a Ph.D. in machine learning and can't find a machine learning "job" and want one, then go to Wall Street and become a quant. Bear in mind that it could also be that these folks don't want a machine learning job, maybe they need to level up their programming skills or are interested in other software engineering related skill sets. There are many programmers who majored in business or physics or even history.. yet they became programmers and some are quite successful! Should they have not been hired because they would eventually leave to go teach history or smash an atom?