Levi Johnston thinks he's cracked the mystery behind Sarah Palin quitting her job as governor of Alaska -- she's all about the Benjamins.
Johnston says Palin was pallin' around with people who were offering the mavericky maverick millions for book deals and reality shows. He says he heard Sarah say she'd love to cash-in on the offers ... and that's why she resigned as governor.
And speakin' of cashin' in -- Johnston's currently pursuing his own book and movie deal. Birds of a feather cash in together.