Who defines Inevitability?

The one-dimensional mindset of the American government during the end of the war created an "inevitable" end to the war that entailed the death of millions. The American government's refusal to accept any outcome except for unconditional surrender forced Japanese to continue fighting for a chance of negotiations. The decision between dropping a bomb killing millions of Japanese and an invasion at the cost of American lives was determined by the engrained ideals of American exceptionalism and prioritization of American lives over Japanese lives. Basically America being stubborn and believing in their superiority created the "inevitable" atomic bomb. While I understand while the American government prioritizing a more favorable outcome for themselves and saving American lives, the decision to target a well-populated city filled with civilians seemed unnecessarily cruel. America could have easily forced unconditional surrender without the needless slaughter of millions of Japanese by targeting resources.