Ok, so how do you explain the situation for chemists? The variation in their productivity due to competence is at least comparable to that of programmers if not more -- yet their pay is uniformly low and the job security is uniformly poor. The only escape route is having the flair (!=competence) required to go into administration or attract investors (which is basically the same thing). OTOH if you assume that supply/demand is king, it all makes sense.

To assume that your competence will save you, you need both to assume that your evaluation of your own skills is correct and that others will confidently agree. Both of those propositions sound shaky. I've met a lot of overconfident programmers and I've met a lot of disinterested HR people.