Why was Moshe not rich before the sin of the Egel
The maharam Shik asks and answers that when Bney Yisrael received the Torah Pashtu Zumahasan but after the Egel this tumah came back. So until that time they were on a level where they would have listened to a “poor” Navi but afterwards this Tumah came back and it was suddenly necessary for Moshe to be wealthy and this was when GD made him wealthy so the Nevuah can continue.