I think this depends on where you are measuring costs in your codebase. If you're strictly looking at time to market on your first iteration, then you're right, types are going to require more of your team's time up front. If you look at the total lifespan of a "real project", then type safety is likely going to represent a cost savings regarding time your team spends on bug fixes, refactoring, and maintaining legacy portions of your app.

For context, I base the above sentiment on our team's last two years of effort in migrating key parts of our app to TypeScript (25 devs, ~500k lines of code). We've found that it has substantially reduced the number of defects that make it into production, and it has also reduced the number of round trips through QA. Clearly, this is only one data point, but hopefully it offers some perspective on why TS can be valuable in a codebase.