Dan PrimackIllustration: Aïda Amer/AxiosWhen startups collapse, the losers usually are direct stakeholders like investors, founders, and employees.But when fintech Synapse went under earlier this year, thousands of users also were left holding the bag. In some cases, that meant their life savings.Catch up quick: Synapse was a middleman, connecting fintechs that didn't have banking licenses with actual banks.It raised just over $50 million in VC funding, most recently in a $33 million Series B ro...