The longest U.S. economic expansion in history has brought news of big spending. It also has raised concerns about the distance between the rich and everyone else. For some people, the high price of some goods is a sign of too much wealth. The bank UBS says the number of billionaires in the United States has increased from 267 in 2008 to 607 in 2018. “The rich have gotten richer and they’ve gotten richer faster,” said John Mathews. He is the head of Private Wealth Management and Ultra High Net Worth at UBS Global Wealth Management. But there are signs of problems at lower-income levels. Information from the U.S. central bank suggests that, by 2016, the richest 20 percent of Americans held 88 percent of the country’s wealth.