That's one reason I dropped out of a PhD program in Math. I realized that, if I was lucky and did well, I would get a tenure-track job at the #250 ranked schoo

That's one reason I dropped out of a PhD program in Math. I realized that, if I was lucky and did well, I would get a tenure-track job at the #250 ranked school. If I was unlucky, I would be perma-adjunct with no other marketable skills at age 40. On the other hand, in software, I'm also feeling washed up at age 40, but at least I earned a decent salary in the meantime, and probably will always be able to find some sort of software-related job.