The Manhattan project cost only $2 billion (about $30 billion adjusting for inflation to today).
It would probably be more reasonable to adjust for US GDP. That would put $2 billion back then at around the same as $250 billion today. So only about 2x off.
alt Hacker News
It would probably be more reasonable to adjust for US GDP. That would put $2 billion back then at around the same as $250 billion today. So only about 2x off.