A philosophy taught to Marty Cagan early in his career: a programming language (or any tool) is just a tool, not an identity to be proprietary about defending.
Practically, this means choosing a language or tool based on fit for the problem at hand rather than personal preference, familiarity, or sunk-cost attachment to what one already knows — and treating the acquisition of new languages/tools as something that broadens career options rather than as a threat to expertise already built.