The passengers for this enormously expensive helicopter fleet? The President of the United States and his entourage.
The first president to fly regularly in helicopters was Dwight Eisenhower. Eisenhower faced a two-hour commute to and from his summer home in Rhode Island, a commute that could be shaved down considerably if taken by helicopter. In these early days of the Cold War the president needed to be moved around quickly—the president could not be stuck on a ferry for an hour in case the Soviet Union launched a nuclear attack.
The South Lawn of the White House was designated as the official presidential helicopter landing pad, and official flights to Andrews Air Force Base began.