There are areas where typing is more important: public interfaces. You don't have to make every piece of your program well-typed. But signatures of your public functions / methods matter a lot, and from them types of many internal things can be inferred.
If your code has a well-typed interface, it's pleasant to work with. If interfaces of the libraries you use are well-typed, you have easier time writing your code (that interacts with them). Eventually you type more and more code you write and alter, and keep reaping the benefits.
This was the thing that started to bring me around to optional typing as well. It makes the most sense to me as a form of documentation - it's really useful to know what types are expected (and returned) by a Python function!
If that's baked into the code itself, your text editor can show inline information - which saves you from having to go and look at the documentation yourself.
I've started trying to add types to my libraries that expose a public API now. I think it's worth the extra effort just for the documentation benefit it provides.
This is what made me give it a shot in TS, but the problem is your types at interface boundaries tend to be annoyingly complex. The other problem is any project with optional types soon becomes a project with required types everywhere.
There might be more merit in widely-used public libraries, though. I don't make those.
I shouldn't have said it's a waste of time period, cause every project I work on does have static typing in two very important places: the RPC or web API (OpenAPI, gRPC, whatever it is), and the relational database. But not in the main JS or Py code. That's all I've ever needed.
I did try migrating a NodeJS backend to TS along with a teammate driving that effort. The type-checking never ended up catching any bugs, and the extra time we spent on that stuff could've gone into better testing instead. So it actually made things more dangerous.
There are areas where typing is more important: public interfaces. You don't have to make every piece of your program well-typed. But signatures of your public functions / methods matter a lot, and from them types of many internal things can be inferred.
If your code has a well-typed interface, it's pleasant to work with. If interfaces of the libraries you use are well-typed, you have easier time writing your code (that interacts with them). Eventually you type more and more code you write and alter, and keep reaping the benefits.