Unless you are writing a compiler and code specifically tailored to take advantage of UB, there’s not much to say about it other than “be careful about UB cause it can make your program buggy from your POV.”

> Are you saying people who learned C as their first programming language are better programmers or worse?

That's both a false dichotomy and irrelevant as well.

My message is "There are multiple excellent (even legendary) developers in the short history of our field that learned programming in C. There are many more who primarily used C".

This refutes your point completely.