You stated how he made his fortune. He did not do it through the government.The federal government has paid SpaceX some $20 billion since 2008. He also was given a 400+ loan under Obama. All of that led to him increasing his net worth. He wants to be a trillionaire, so don't sleep on him not finding out ways to make money out of this.
He did it through Pay Pal and Tesla. Either are government driver enterprises. It is well documented.
Going forward, yes, in certain areas of spend there are conflicts of interests.