Writing correct C is REALLY hard and slow (strings, manual memory management, concurrency pitfalls). So the investment is not paying off unless you are writing highly performance critical backend services.

What can pay-off is learning to read C. Node.js, Firefox, Postgres, Linux are all written in C/C++ so if you ever want to really understand what's going on or have to debug a nasty bug, then you will need to be able to find your way around these code-bases.

Not really, but it depends. For instance, C is pretty great for compiling simple logic into WASM modules because the size overhead is minimal compared to most higher-level languages, or even C++ with careless use of the stdlib (and the missing memory safety isn't such a critical problem because everything runs in the WASM sandbox anyway).

E.g. I think the size of my WASM demos is quite reasonable for what they do:

https://floooh.github.io/tiny8bit/

https://floooh.github.io/sokol-html5/

However, AssemblyScript is also a pretty good choice for this type of stuff from what I'm hearing (while for instance languages with a complex runtime like C# are not).

I find that there is a lot of value in learning "how the sausage is made". Implementing your own baby version of the things you take for granted in higher-level languages is an interesting exercise — e.g. things like dynamic dispatch.

These are things that are not directly useful, but help you have a better mental model of how your language of choice actually works.

C is a low level language that compiles down directly to assembly. It is similar to Go in this regard, but is a bit lower level. You have to manage memory yourself and pointers in C are much more dangerous. Reasons to learn C would include: absolute performance needed maybe for say a Python C extension, kernel hacking, some other project you want to contribute to uses C.

I think it’s good to at least play with C and understand how memory management and pointers in C work, but I don’t think I would recommend you go out of your way to learn C or spend any significant amount of time writing it. At the end of the day it’s just another tool in the toolbox. I would recommend the book Code, by Petzold, if you want to really want to explore computers at a low level in a friendly format.

If you're interested in:

-Embedded/cyber-physical systems software (firmware dev)

-Driver development (applies to Win/macOS/UNIX/iOS/Android)

-Contributing to the Linux kernel/OS dev in general

-Contributing to many large OSS projects (Apache, ffmpeg)

-Exploit/malware dev/reverse engineering

-Emulator development

you'd need to learn C.

Your question is too vague. Are there benefits in general? Of course, every language has something to offer.

Is it useful as a web developer? Only if you want to write extensions to Python in C or step away from the web developer label and learn systems programming.

For you, yes: you will better understand Python's source code, which is written in C. Poke around the source code a bit just out of curiosity after learning a bit of C and it becomes a bit interesting.