I don't think you understand the benefits of type checkers. Here are some:

- Catching at compile time errors that would otherwise happen at runtime

- Performance

- Occasionally, it can enable making your code mathematically, provably correct

- Maintainability and flexibility in the sense that the code is easier to read by future hires

- And the most important advantage of all: automatic refactorings. Without that, the code base rots because developers are afraid to refactor since doing this without errors on a dynamically typed language requires a lot of tests, which nobody really has. Even renaming a function cannot be done safely in a dynamically typed language and it requires the oversight of a human