Fair enough, but I think Munich is an interesting case, and I was disappointed to find on opening the thread that it was not specifically about Munich, but about exonyms in general.
The term “exonym” refers to local names for foreign places, and there is no general answer to the general question of why they exist. The answer in a specific case is often interesting, however.
In the case of “Munich”, we have an English version that looks like a German word, and moreover is not pronounced according to English spelling norms, but more like an English approximation of how it would be pronounced if it were a German word.
The French (from whom we presumably borrowed the word) use the same spelling “Munich” but with French pronunciation.