“a teacher in the yeshiva I attended tried to convince me that Avraham Aveenu and Moshe Rabaynu wore black hats.”
And we wonder why so many people go off the derech.
Rambam never wore a black fedora.
Neither did the Remah.
Neither did the Vilna Gaon.
In fact, neither did the Chofetz Chaim, even though by the end of his life they had become common dress in non-Jewish circles. (I heard this directly from a RY who learned in the CC’s yeshiva while the CC was still alive.)