I attended a few conference/training (POPL/OPLSS) that made me want to pursue more chalenging things in computer science. Among other things my terrible grades in Comp.Sci in the early 2000s required me to do another bachelor's degree to open up masters/phd programs. In other words I was leaving the company.

Not a single developers there had bothered (such a bother /s) to learn F# and I wanted to make sure they didn't depend on me. It all worked out perfectly because the math degree turns out to be much more challenging than computer science.

Unfortunately developers overestimate the amount of work required to learn a new programming language. In particular ones on the same platform (say F# on .NET for a C# dev). It turns out that learning the libraries takes years but learning a new PL takes but a couple of days of focused efforts.