Why did it take so long to bomb and level hanoi

It is my belief that it is the US governments falt that we lost the war. They didn't care who got killed, who did what , or who it was done. They just wanted to make money and keep their jobs while the war was going on. Had we bombed Hanoi first before making it a ground war, we would have broke down moral and limmited the numbers off Viet COng left to fight. Also the area of The Ho Chi Ming Trail should have been leveled by B-52's and Phantoms severaltimes over, but it was never done because the US government wanted to milk the War as much as they could before we won it. But they waited to long and the Viet Cong, led by a very intelligent leader, made his move and took the victory.