Despite the bomb, the work done on the Manhattan project has lead to many other discoveries too, like nuclear energy. Like others have said, it was inevitable that the bomb would have been discovered, and I think using the bomb in Japan probably helped stop a nuclear exchange during the Cold War. Nuclear weapons are terrible things but I think in the long run humankind will be better off because of the good that nuclear technology can bring us.
You may well be right as long as the bombs remain in rational hands.
OswaldTheOsprey