The founders of Collective Health, a Silicon Valley startup, say they can help employers save money by self-insuring rather than paying premiums to a health insurance company. Collective Health has developed software to help companies pay workers' health costs directly. Collective Health describes its "sweet spot" as companies with a few hundred or a few thousand employees, typically in the tech sector."Insurance providers make money by overpricing risk and underpaying care," said Collective Health's Chief Executive Officer Ali Diab, whose previous company AdMob was acquired by Google Inc.