Prove how?
By means of natural selection. They could have succeeded in spite of
dynamic typing, not because of it.
You think the otherwise smart and successfull founders of these projects all made the wrong choice when it came to selecting the right tool for the job? Facebook defined a new programming language
No, they wrote a faster runtime. to add static typing to HHVM
No, they added type annotations. There’s a lack of good statically-typed languages
No, in the past statically typed languages were the norm. C, C++, Java...It's just that dynamic languages outcompeted them.