I didn't give any career advice at all. Why did you think this was it? My career advice would be to keep developing in whatever established and practical language you are using and get paid to use if that's what you want.
But as I started a new project which eventually could be a business, then I can use whatever language I want, as long as it's practical for my use case. Why would I use any other language than one that I already know and like? It would make no sense. If you were to start your project, you would probably pick a language you enjoy using, rather than the one you are paid to use, unless it happens to be the same.