No one in the world is less able to make that accusation than the current President. Whatever the state of their monetary payments, most of the 28 member nations of NATO have fought in America's wars. And their men, some of them draftees, have died in the wars in Iraq and Afghanistan. Our Draft-Dodger-in-Chief, who avoided the Vietnam War, feels free to attack allies who sent men to die in wars we started.
The issue with NATO should be blood as well as many. The NATO charter includes a mutual defense clause, what is essentially a "Three Musketeers" clause: All for One and One for All. The ONLY time that clause was invoked was on September 11, 2001, when NATO nations came to our defense.
An honorable man would know that when men serve and die for you, you owe a debt of honor. Only a coward would reduce that debt to money. Character is Destiny, said Aristotle 2,500 years ago. He is still correct. Only a man who let another man serve in his place could see NATO as another "Let's Make a Deal" transaction.