There’s a lot of problems with C, like the fact you have to break out of case statements, or string concatenation, or overuse of the static keyword. These are actual problems, which C++ doesn’t even begin to try and solve, instead introducing useless features and bloat. C is still one of the few popular languages that allows you to talk to the machine directly. It’s a language that doesn’t rely on hidden run-time logic, or hidden implementation costs. It doesn’t enforce any particular programming style on you, and lets you do anything a process is capable of doing.
Software engineers these days are so lost in abstractions and design patterns that they forget that at the end of the day a program is just data, and a set of operations that transform that data. There’s huge value in writing code that does everything explicitly from top to bottom, both from a readability, and from a debugability standpoint. Instead, these days, software is designed using UML diagrams and OOP concepts while pretending that objects are ideas that float in some abstract disconnected space. All in the name of concepts envisioned by people who write books instead of programming, and who never saw even a glimpse of a problem you’re trying to solve.
Languages like C will never become obsolete. There’s always a new frontier of hardware that needs fast, tailored software. Few years ago that was phones, and watches, next it might be tiny implants. Anybody who thinks languages like C is obsolete should ask themselves “why was my Comodore64 more responsive than a PC i bought in 2016?”, or "why is my dual-core Android smartphone with 1GB of RAM barely usable after a year”. Modern languages and programming practices have this amazing ability to completely negate the massive progress hardware has made.