In another variant of https://danluu.com/learn-what/, I caught up with a former colleague who worked on automated theorem proving. It turns out he's had an interesting career doing all sorts of interesting stuff using the skills he developed by spending a decade writing/using theorem provers. At one point, he said, "if you use X like a theorem prover, it works really well", which surprised me to hear, but of course this is a highly generalizable skill just like compilers or benchmarking/evals.