Math genius Grigori Perelman, considered to be one of the world's most intelligent persons, turned down a one million dollar prize for solving what was thought to be an unsolvable problem. He says he is not interested in money, only knowledge
The Poincare conjecture was a seemingly unsolvable theorem that was first proposed in 1904. Dealing with a branch of spatial mathematics called topology, the theorem sought to prove that any shape without a hole can be formed into a sphere. Sounds simple enough, right? Tell that to the math world, which, for over a century, struggled to prove the elusive conjecture even possible, inadvertently turning it into one of the community's Holy Grails.
Russian mathematician Grigory Perelman:
http://techland.time.com/2011/05/03/...-dollar-prize/