Musar על יומא 144:7

There were three "crowns" as we mentioned earlier. The reason they are referred to as זרים rather than as כתרים, is to reflect the statement of our sages who have said that "he who merits a crown, זר, spelled with the vowel Tzeyreh, does not need to worry about the זר spelled with the vowel kametz. Of the latter the Torah has written: והזר הקרב יומת, "The stranger who approaches will be executed" (Numbers 1,51). What our sages meant was that he who studies Torah in order to observe its precepts, is fortunate and will be crowned with the crown of Torah. If, however, someone is a Torah scholar, preaching Torah values but personally not practising them, he will eventually become totally estranged and his punishment will be twice that of people who do not have Torah knowledge. The reason is that the Torah scholar used to be קרוב, close, whereas now he has become זר, estranged.