I have >20, in a mix of dynamic and statically typed languages. I've even designed a few of both including some that straddle the line.
> It's a shame to see the new generation of developers moving back to statically typed languages
It's only a shame if you presume to know better than all of those developers. If dynamic typing was what they wanted, they wouldn't have added TypeScript to their existing JavaScript code. Personally, I trust that in the aggregate, developers aren't dumb and do understand their own pain points and solutions even when the pain and solutions aren't obvious to me.
> Many of the people who came up with or promoted the idea of dynamically typed languages had decades of experience working with punchcards, assembly code and statically typed languages; they were onto something.
Most of the designers of the initial statically typed languages came from that same era and technology background, so I don't think this argument carries much weight.
Neither dynamic nor static typing supplanted the other. They are parallel tracks and have been for virtually all of computing history (see BASIC and FORTRAN). Both branches are still going strong, so anyone on one branch isn't discarding the wisdom of the other, they're simply choosing their preferred path. If I use a hammer and you use a screwdriver, I'm not "discarding the vast amount of screwdriver wisdom", I simply know that I have a nail and not a screw to deal with.
One of the real problems I see with advocates of dynamic typing is that we for the most part, we have lost a dynamic code editing experience. Without something like Smalltalk's "open a code editor when an error occurs" live debugging/editing experience, you'll never get the real benefits of dynamic typing.
Editing dynamically typed code in a textual static user experience seems like the worst of both worlds to me.