NASA investigated the Falcon 9's development costs because the standard NASA Air Force Cost Model (NAFCOM), which works so well for NASA and Air Force rocket development, produced an initial estimate that the Falcon 9 should have cost $3.97 billion dollars to develop, not the less than $400 million SpaceX spent.
NAFCOM Falcon 9 analysis
By the way, SpaceX was founded in 2002, developed their own engines, tanks, guidance system, and everything else, and was launching into orbit by 2006. By 2010 they became the first private company to put a capsule in orbit and return it, and that capsule was designed to hold a crew of seven.
NASA says the total development cost on the SLS/Orion will be about $35 billion, which, under the Falcon 9 development cost structure, would be enough to develop about eighty
unique, private sector orbital launch vehicles.
Or, in a world where NASA was actually efficient instead of burdened with a legacy of "money is no object" ICBM hardware, military aerospace contracting practices, centers cited for Congressional district support instead of common sense, etc, the SLS should cost about $3 billion to develop over a couple of years, since they're just re-using existing engines, tanks, and boosters.
For example, Gemini was actually our third manned space project, started about seven months after Apollo when we realized we needed something after Mercury but before Apollo hardware was ready. Born in 1962, Gemini had its first flight in the spring of 1964. Of course, one of the ways we were getting the projects to move so quickly, given that we were learning
how to even build such things at the time, was that the government treated it like WW-II. Just throw millions of people and billions of dollars at a problem and they'll solve it. It's extremely
inefficient, but it works. For example, it's estimated that Apollo employed 400,000 people and cost somewhere between $110 billion and $180 billion modern dollars. Currently NASA employs about 18,000 people and 70,000 contractors. NASA make look back at their past budgets and employment levels and think they're doing pretty well with what they have, while SpaceX, the giant among newspace startups, employs about 3,000 people.
If it takes 10,000 or 20,000 people on the ground to keep each person in orbit, you're obviously never going to put many people into orbit, and for each person in orbit someone has to pay the salary of all those people on the ground. The solution is to build rockets using less money and fewer employees instead of bloating the budget so the same inefficient system can just get "embiggified".