[Cthulhu_]

This is true, but it doesn't mean you should actually use a variety of languages for your day job if you're self-employed; that is, you lose some productivity if you choose an unfamiliar tool, and you'll shoot yourself in the foot if you choose a language unsuitable for the problem at hand.

The other thing to watch out for if you're in a corporate setting is that if you use a language nobody else is using at your company, your project is doomed and / or it will be stupid expensive compared to other projects because it uses a different language from the rest of the organization. See also https://boringtechnology.club/