In general it sounds like you are doing what I would do (show them that it can be introduced gradually/non-disruptively, and what problems it solves). However,

In general it sounds like you are doing what I would do (show them that it can be introduced gradually/non-disruptively, and what problems it solves). However, you can't always do a whole lot to change a culturally embedded prejudice against certain practices/technology. The best I could really think of doing is just waiting until bugs are inevitably found, and documenting each case that could have been avoided by the compiler. If your company tracks work done, you could come to your technical leadership and say "we wasted 200 hours this quarter/year/whatever fixing TypeErrors that TS would have caught", and that _might_ move the needle. You can't change the opinion of a horde of developers by talking to them directly, but if a mandate comes to them from on high that's for their own good, that will probably at least get some of them to try it long enough to come around to the idea. Even that idea is kind of politically risky though, so take it with a grain of salt.