Billionaires and professional politicians all have skeletons their opponents can use to blackmail.
Politicians in developed countries don't have enough money to pay off blackmailers. That's why - except in dictatorships - sleazes tend to avoid politics. Self-made billionaires like Bloomberg and Jobs are far too busy building their empires to dabble in sleazy affairs with married women, which take up considerable amounts of energy and time. Women have be courted and cajoled into jumping into bed, which is why many charismatic, popular and good-looking showbiz figures and sports figures prefer the company of prostitutes. And for politicians, the risk of exposure isn't limited to chatty paramours - it extends to service personnel at restaurants, bars, hotels, et al, and well as the relatives and friends of the paramour, all of whom could spill the beans for mere thousands of dollars to a newspaper or news network.
Note also that blackmail involves considerable risk to the person trying to extort money. Blackmail is a felony punishable with a lengthy prison term. There’s no guarantee that throughout the extended and risky back-and-forth haggling over money, somebody else also in the know won’t go to the press and spill the beans for cash, leaving him facing a criminal prosecution when the person being blackmailed tells of the blackmail attempt.