You never reach a phase when you can confidently say that you understand git. But it's certainly possible to go from "When something goes wrong, I just delete the repo and clone it again" to "Aha! Now I can deal with most of the issues".
Mine was when I realized that git commands come in two flavors. Those that deal with commits as snapshots (commit, checkout, switch, reset, etc) and those that deal with commits as changes/diffs/deltas (merge, rebase, cherrypick, revert, etc). (Note: This isn't about how git stores commits on disk). I believe that this is actually the main source of confusion for beginner and intermediate git users.
That's misinformation. There's no overestimation. The problem is so bad that even the US government advocates the use of memory safe languages (including GC languages).
I have used C and C++. You need laser sharp focus to avoid memory safety errors even after you learn what causes them and how to avoid them. It's significantly easier to write programs in Rust because any lapse in care to avoid memory safety bugs are caught by the compiler.