The process of developing a new programming language and maintaining said language is a rather expensive affair, it does beg the question, why do we have new ones coming out of the woodwork every now and then?
Massive organizations need these languages to improve on some aspects of their production that other languages are found lacking in terms of efficiency, the other answer is that while most languages are free to use, it's not guaranteed that it'll stay that way. Having to pay royalty in order to continue to use a programming language is a concern that prompts organizations to develop their language.
For companies with a huge ecosystem (coughs Microsoft coughs), there's a sprinkle of ego in it. When you're that big and most of your products are immaterial you need to have end to end software programming languages, to not just to have them alone but to make sure they're the best in order to attract top talent that will continue to grow products for the company, make no mistake, companies pay attention to the popularity of their language. Because these companies created their language they're stuck with it, they need to find a way to ensure the language remains competitive so as not to lose developers who are rather fickle.