They did it with their own profit motive in mind. They expanded westward and settled the country for their own personal benefit. Fur trapping, farming, ranching, the lumber industry, mining, etc, etc.
If it's worthwhile, the government doesn't have to provide "incentives". The government just need to keep the heck out of the way. And part of keeping out of the way means not confiscating money that people might have a better use for, just to waste it it on frivolous ventures with no point other some politician's vanity.
You obviously didn’t listen to the speech. This is not a government project; NASA will function mainly as a coordinating agency for private entities, doing things like making sure onerous requirements (such as the EPA) and red tape don’t get in the way. The budget for NASA will actually be reduced, because it won’t be doing the work.
The work - as in the building of the railroads - will be done by people who have the guts and the money to go out there and try it, and it will employ huge numbers of people as soon as it starts up, ranging from top-level scientists to the people who run the roach coaches at the building sites.