Study math for long enough and you will likely have cursed Pythagoras's name, or said "praise be to Pythagoras" if you're a bit of a fan of triangles.
But while Pythagoras was an important historical figure in the development of mathematics, he did not figure out the equation most associated with him (a2 + b2 = c2). In fact, there is an ancient Babylonian tablet (by the catchy name of IM 67118) which uses the Pythagorean theorem to solve the length of a diagonal inside a rectangle. The tablet, likely used for teaching, dates from 1770 BCE – centuries before Pythagoras was born in around 570 BCE.
Pythagoras was a brutal cult leader, wasn't he?
Considering that we're somewhere on a scale going from "We're not really sure Pythagoras was even an actual person" to "Pythagoras was a brutal cult leader". My stance will be that the theorem is useful, and that Fermat, Fourier, and Laplace, apart from being French (which is bad enough to begin with), also made math hard on me in university, at least the last two. Fermat was just a dick with that margin note. Curses on all three of them!