You should learn C because it's a gateway to deeper knowledge. The kernel uses it, about a thousand programs shipped with Linux use it, embedded programming uses it. It helps you understand how lower level network protocols have been designed, how to efficiently use memory, how to design algorithms and why they're harder than you think. There's a crapton of libraries in C, most higher level languages have some extensions to take advantage of them. Sensitive security software will use it, due to various attack vectors that are slightly easier to deal with at a lower level. It's handy and expands your brain. And it's not going away anytime soon.