Who is the biggest crank?

People inventing complex mathematical models that are perfectly mathematical correct, but that are based on a series of flawed assumptions that breaks down completely in practice. And yes these models are marketed to practice, some times with disastrous results.

or someone

that invents a machine by trail and error that in practice seems to be able to do what no one though would be possible. The inventor cannot explain exactly why it works. It was build by trail and error (at some point the inventor was “lucky”), like the nature itself often evolves. The few so called scientist that even bother commenting on it claims it must be nonsense because where is the mathematical evidence, where is the scientific theory? They do not even bother looking at such a machine, they have made up their mind.