Cpl Joshua Caldwell, I had many conversations with my father on this subject. My father, LTJG Jack Curlee, was the engineering officer aboard USS LST-78 for a year or more in the Pacific and continued as WWII ended. An LST was the largest naval vessel that could actually be beached to disgorge men and materiel.
My father, his shipmates and probably the entire US Navy were well aware of Operation Downfall, and may have even been preparing for the invasion. The estimated casualties of the invasion vary, but due to the Japanese mindset (military and civilian) to fight to the bitter end, the number could easily have been a million or more.
Thus, my father concluded that had the US (Truman specifically) not dropped the atomic bombs to end the war with Japan, he very likely would have died during the invasion, and I wouldn't be here writing this anecdote. I tend to agree with my father.
I think you'd find very few servicemen (that served in the Pacific especially) that felt otherwise. LTC John Mohor

I was in Kansas City, Mo a couple years back attending the Veterans of the Battle of The Bulge Mational Reunion on the day we toured the Truman Library. I saw written in comments at the Atom Bom Decision display from a number of 87th Infantry Division Vets that attended thanking President Truman for making the decision he did because they all felt that one decision saved their lives! Had it not occurred the 87th along with numerous other Servicemembers where scheduled to participate in the invasion of the Japanese Home Islands.

My uncle left Pearl Harbor on a troopship at 1400 local time on Dec 6, 1941 after completing his enlistment to be separated for the USArmy upon arrival in CONUS. Obviously, he didn't arrive in CONUS as anticipated. He served the rest of the war as a combat infantryman seeing combat in New Guinea, then in Europe landing in the Third wave on Omaha Beach and continuing to the Elbe River. He served the entire war as a front line infantryman without ever being wounded. The first week home after the war his car skidded on a muddy road and a pistol in his glove discharged and hit Him In the leg. He stated many times that neither the Japanese nor the Germans could hit him and the only way he could get shot was to accidentally shoot himself. He retired in 1964.