I, for one, find the TIOBE index absolutely incredible - ie, I don't believe it at all. As it says:

"The index can be used to check whether your programming skills are still up to date"

C is #2. Javascript, for better or worse the most important language for web dev, is #8. So what is this list implying - that JS developers should get with the times and learn C?

Without details on how this list is compiled, I think it's pretty useless. Even the most cursory search of any job site will show orders of magnitudes more jobs for "unpopular" languages like JS, ruby and golang than for C. I'm not even sure what C is used for these days beyond kernel/driver development or embedded systems. I think I've met precisely one C developer in the last 10 years.

Maybe I live in a bubble but this list just seems divorced from (my) reality.

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.

Maybe you live in a bubble too. That's just a guess but a majority of windows programs may be made in C#

On the contrary, I also regularly work in depth with JavaScript, TypeScript, Python, Golang, Java, Scala, Rust, C#, Perl, assembly, and more, in no particular order, and I routinely work as a sysadmin, network administrator, and operations. I may live in a bubble but I'd say it's of adequate breadth to judge the relevative scales of many ecosystems.

That's quite the repertoire, so you mind if I ask what your role/position is?