Personally, I find Bishop's book to hit on a good balance between developing intuition and presenting the math to give precision to understanding (the opposite of this would be Murphy's book--the math seems too esoteric and disjointed to be useful). I have a hard time feeling confident I thoroughly understand a concept without having precision in the presentation of the math behind the concept.

There is certainly something to be said for courses and books that can present a complex idea without requiring a graduate-level degree of math literacy. But at the end of the day, ML is a subfield of mathematics so not having a thorough grasp of the math underlying it will definitely hinder your understanding.