Most of those "billions of dollars" have been made via inflating the private and public debt, and some of them using eminent domain to confiscate the property of others.
Last night on a thread, the pro-Trump crowd was up in arms defending his business practice of loading up debt on a business, then declaring bankruptcy leaving the taxpayers to clean it up. They said it was ‘smart business’. I can’t wait to see if they call his use of eminent domain ‘smart business’.