There is no "one" cool programming language, yes, but there are only three. Perl is not one of them. Neither is Java, Python, or Lisp. Judging just from Google search results, Perl has 84,700,000 results, while JavaScript has 2,150,000,000, PHP has 7,530,000,000, and C is a little too vague to search for but I think its popularity is quite evident, it's less popular and more required.
So, we have three "cool languages", C/C++ for operating system software (this is indisputable, all other languages aren't fast enough), PHP for server-side software (other languages aren't feature-rich enough, or aren't easy enough to allow fast development), and JavaScript for client-side software (where there exists literally no alternative).
JavaScript is also quickly growing as a replacement for both server-side and operating system software, as it runs on any platform, is faster than both PHP and Python and is becoming more feature-rich all the time. One could easily settle on learning only the languages used on the web, and make a happy living. I think your view of a multi-language world is not accurate to reality. More and more the tech world is becoming single-language, with every user at a web browser, and JavaScript running everywhere and everything.
So, we have three "cool languages", C/C++ for operating system software (this is indisputable, all other languages aren't fast enough), PHP for server-side software (other languages aren't feature-rich enough, or aren't easy enough to allow fast development), and JavaScript for client-side software (where there exists literally no alternative).
JavaScript is also quickly growing as a replacement for both server-side and operating system software, as it runs on any platform, is faster than both PHP and Python and is becoming more feature-rich all the time. One could easily settle on learning only the languages used on the web, and make a happy living. I think your view of a multi-language world is not accurate to reality. More and more the tech world is becoming single-language, with every user at a web browser, and JavaScript running everywhere and everything.