A lot of mathematicians made fun of imaginary numbers when they were first proposed. In fact, the name “imaginary numbers” was actually given by skeptics to make fun of it. It kinda makes sense, imaginary numbers are all based off of a couple fairly strange assumptions, but they make otherwise difficult problems solvable.
The whole thing kinda ruined math though. Nowadays, mathematicians spend their entire careers building frameworks based on silly assumptions in the hopes that one day it’ll be useful.