Compare it to another engineering project of national importance: the Apollo mission to land man on the moon. It cost $25.8 billion between 1960 and 1973, or $257 billion in 2020 dollars[1].
Both were massive and urgent projects, but the atomic bomb cost 5% of what Apollo cost. An unexpected bargain.
E.g. in 2023, the U.S. GDP was approximately $25 trillion. 1% of that is about $250 billion.
What comes to mind is that it’s pretty important to keep an airplane in the air, which must require a lot of careful engineering. Also that you have to make a lot of them. A bomb doesn’t really have either engineering requirements. (Only has to work once, they only made a few)
I also wonder to what degree cost was saved by getting all those highly talented and motivated refugees from europe
Prior to that bomber crews operated using electrically heated flight suites, gloves and used oxygen masks, when reaching those altitudes.
http://www.303rdbg.com/uniforms-gear3.html https://en.wikipedia.org/wiki/Boeing_B-29_Superfortress#Pres...
After Fat Man & Little Boy, it's obvious we didn't just stop building bombs. The Manhattan Project's main development was the proof that the bomb was possible. Much more money followed making new versions that were even more powerful.