Earlier this month, top Swiss business leaders arrived at the White House bearing lavish gifts fit for a king. The chief executive of Rolex gave President Trump a gold-plated desk clock. Not to be outdone, the chief executive of a gold-refining company presented him with a 2-pound gold bar engraved with 45 and 47, in honor of his two presidencies. A week later, the president rewarded Switzerland with a favorable break on tariffs, reducing them from 39 percent to 15 percent. The Trump family earned $3.4 billion through deals it had arranged since Trump entered the White House in 2017.