It is boom & bust. When wages rise "too high" then the media is full of "shortage of X". Youngsters see that, switch to that career, then a couple years later t

It is boom & bust. When wages rise "too high" then the media is full of "shortage of X". Youngsters see that, switch to that career, then a couple years later the glut of workers drives wages down until people quit, wages rise and the media is filled again with "shortage of X".