At what point does mathematics get hard?

There is a point where math gets hard for anybody and everybody. For some it’s high school, for others college, undergraduate or graduate study, or even research-level math, and there most problems are really hard.

Do not assume that 90’s in all math classes at high school imply that you won’t find any difficulty with college math. You probably still haven’t been taught math in a rigorous way.

You need to have a healthy respect, and know, but not fear, that you will have difficulties with some ideas at first. But as long as you are passionate, it will be fine, and you will do well.