sell the farm
To risk all of one's assents on a venture that one thinks will be hugely successful or rewarding. I wouldn't sell the farm on that wacky invention. He's broke now because he sold the farm on a foolish business venture.
sell the farm
and bet the farmFig. to liquidate all one's assets in order to raise money to invest in something. It's a risky proposition. I wouldn't bet the farm on it.