You 100% live in a bubble.
First of all, I'm a C developer. Hi!
Second of all, web developers are not the majority they think they are. The internet is huge, sure, but remember it's not just running on web browsers. It's also running on servers which have network interfaces that need drivers and implementations of the IP suite, through firewalls, routers, switches, and load balancers that are all written in C, and running your trendy web app in a hypervisor that's written in C. Your database - be it PostgreSQL, MariaDB, Redis, etc - it's written in C. Your web browser uses C for loads of stuff like sqlite, rendering, etc. The Python and Ruby interpreters are written in C. The .NET CLR is written in C, too.
Beyond the internet, C has an even more pronounced presence. Every microcontroller around you - your fridge, microwave, coffee machine, car, subway train - all written in C. The code on your phone is at least 50% written in C. Your fancy mouse and keyboard? C. Manufacturing robots in factories are coded in C. CNC machines and PNP machines are written in C. 3D printers are programmed in C. Airplanes are programmed in C, and trains and boats too. All spacecraft are programmed in C, from the Curiosity rover to the Rosetta spacecraft (and it's lander) to the international space station.
All of your utilities like grep, ls, git - written in C. So is the code that's decoding the music you're listening to right now, and the YouTube video you watched earlier, and most other multimedia code is C. Your crypto libraries are written in C. Compression algorithms are usually implemented in C. Most font rendering is done in C. Nginx, postfix, openssh - C.
All that being said, TIOBE is probably bullshit. I can't imagine C isn't #1.