In this articleGRMNTSNAXPUPSTGetty ImagesAt American Express, consumers are continuing to open high-fee credit cards and splurge on luxuries like travel. But for lending firm Upstart, there's a strong interest in microloans as cash-strapped Americans try to scrape by.That juxtaposition underscores the growing picture of bifurcation among income brackets in America. And adds to an increasingly popular view that the U.S. is experiencing a "K"-shaped recovery since the end of the pandemic, where higher income ...