"programming is rather thankless. u see your works become replaced by superior ones in a year. unable to run at all in a few more"
... and I can't help but think that this experience is disproportionately part of the Ruby community he was embroiled in. I did some Ruby-on-Rails development back in the day, and yeah... It's all completely un-runnable now. But that mostly seems to be a Rails-specific issue, where the ecosystem was downright hostile to calcification of APIs, workflows, and core tools. A person could publish a whole book and have 50% of its recommendations obsoleted within two years. That has to be demoralizing for an educator and communicator. Contrast that massively with Windows binaries that still run that were built against operating system versions that existed before college graduates were born.
Various other ecosystems lack the high-speed code churn problem. I think even the Ruby ecosystem has cooled from its white-hot molten state a decade ago.