I understand why the OP likes C. I was looking at a couple of old projects of mine and I remember the satisfaction at least in one (a SASL library) of how I made various classes of error impossible using a fairly simple strategy and my own string handling routines. In a memory safe language with lots of assistance for threading there would never have been that pleasure. It was not amazing or anything but it was elegant to my eyes.

I feel I have to develop an economy of effort in C because there usually isn't a dumb and easy way to do things - this pleases me.

C has a mental model that seems relatively simple - I feel I can reason about what's going to happen to a greater degree than higher level languages.

C++ is the worst IMO because it has lots of abstractions but they don't make programming simpler because you pretty well have to understand the low level aspect of what they're doing to get performance - so the complexity is much greater.

Rust seems to put a lot of difficulty up front which is of no value in the kind of typical short program I write most of the time. I just didn't enjoy it. If I had something complicated to do I might eventually appreciate it.

The more high-level the language the less one tends to understand it and that's unsatisfying.

Having said all of that though, I tend to "just write python" whenever I can. If it's a throwaway program one doesn't need more and if it turns out to be necessary to interface to some library or other I know C well enough to sort that kind of thing out. I use threading.....never - at least never by choice.