KEY POINTS: * For customers, fintech promised the best of both worlds: The innovation, ease of use and fun of the newest apps combined with the safety of government-backed accounts held at real banks. * The collapse of middleman Synapse has revealed fintech’s promise of safety as a mirage. More than 100,000 Americans with $265 million in deposits have been locked out of their accounts. * The implications of this disaster may be far-reaching. The most popular banking apps in the country, including Block’s Cash App, PayPal and Chime, partner with banks instead of owning them. * CNBC reached out...