You apparently know little about war, either historically or in its present incarnation. From your postings, you know particularly little about the Vietnam War; which means you know even less about our present wars, as the philosophies that caused them were spawned by our defeat in Vietnam.
War is a tool of foreign policy; to 'win' one you must achieve a desired political goal. "Killing enough people", even if that were remotely possible during the Vietnam War, which it was not for a variety of reasons (although we certainly killed plenty), is not a political end and therefore does not constitute winning unless it is a war of extermination. Now, you may be in favor of the U.S. committing genocide; most of the rest of us are not.
Nearly all serious historians agree that we could not have 'won' the war in Vietnam under any military circumstances. The war was politically unpopular from early on and became more so as it dragged on. It probably could have been conducted differently had we not been a democracy, but then again giant spaceships could have landed and taken us all to the Forbidden Planet, too. The U.S. fundamentally misunderstood the situation from the beginning, mistaking a civil and anti-colonial war for a communist insurgence, so it's mission was unclear at best and non-existent during the worst phases. The only way the U.S. could have 'won' in Vietnam would have been to heed Ho Chi Min's plea for independence in 1946 (communicated through several letters to Truman) and help them negotiate it with the French at that time. Instead we actually forced the French to hand their failed colonial war over to us so that we could re-shape it into a struggle against communism. At the time, less than 20% of Ho Chi Min's movement was communist, but that % grew, of course, as America's Cold War rivals began to support the Viet Min. It just got worse from there.
By the time the 60s rolled around, Vietnam was already an unsolveable clusterfuck for the U.S. It was a human tragedy of immense proportion that we did not recognize and act on that realization until the mid 70s.