Are most math professors generally bad teachers in college/university?

I am going to be taking both linear algebra I and calculus I in my first semester of university in semptembre, along with 3 other courses (one of them being physics). I understand that math professors are generally researchers who have to do teaching on the side, even if they don't want to teach. Does this mean that most students generally have to teach themselves most of the concepts and the professor just goes over textbook examples on a power-point slide? If yes, is it possible I can teach myself most of the concepts of both linear algebra and calculus I over the summer, seeing as I would be doing just that any way when taking the course?