Well, yes and no. Sure, it would be best if you learn all of them, but that's just impossible and not terribly useful. What "Should I learn X" is implicitly "

Well, yes and no. Sure, it would be best if you learn all of them, but that's just impossible and not terribly useful. What "Should I learn X" is implicitly "Given limited lifespan, will learning X, pay off for me". Both in the literal sense like a well payed job and in the sense of making you a better programmer, which kinda depends on your previous experiences (e.g. learning Lisp dialect is kinda worthless, if you already know another Lisp dialect, learning C# pays less if you already know Java and F#).