My startup is build on Elixir for two reasons

1.) The nature of the problem (Distributed Multiplayer Game with complex logic but not computation heavy/number crunchy)

2.) I just like the language and have used it professionally for years

The value of #2 can't be overstated. In my experience, for some (most?) applications, the tech stack doesn't really matter. What tends to be more important is being comfortable with the language enough to iterate quickly and deliver value to customers