Is learning C really a must for a programmer?

Many have this opinion. Somehow, by doing manual memory management allocation and garbage mangement one would become a better programmer.

I have little experience in C mainly because I can write terser and more readable code in Racket or Haskell. However I'm willing to give C a try just to learn these lessons that everybody keeps talking.

But I have a sneaking suspicion that I already know most of what is there to know. Can you list some useful lessons that a typical high level code dweller would be oblivious of?

Most people recommend learning C because it teaches you the fundamentals of programming in a strict environment & stops a lot of people from pursuing programming as a career.  If you can't handle simple C coding, you'd only be a burden to whoever hired you for anything serious.   

A couple years ago, I took an intro C course in college for EE (I just needed the credits) and I've never seen so much anguish.  Pointers ruined hipster dreams.  Empowered womyn cracked under the pressure of structs.  The ubernerd who decided to bring his tank-like gaymen laptop everywhere couldn't figure out how to SSH to compile his helloworld that wasn't going to run anyway.  Absolutely delicious Schadenfreude.