There's a difference between a flawed proof (e.g. Wiles's original proof of FLT which was found to contain a gap) and outright crankery, though. There are more

There's a difference between a flawed proof (e.g. Wiles's original proof of FLT which was found to contain a gap) and outright crankery, though. There are more mathematical cranks than most people would think, and their arguments usually fall apart rather easily.