Tesla got a shitload of government funding, including a 465 million dollar loan [1]. SpaceX was effectively funded by NASA in its early days. In total, the Muskverse alone got 38 billion dollars [2]. Bezos' Blue Origin got at least 1.5 billion dollars [3].
Sure, by number most startups are fully privately funded. But that doesn't mean the US government isn't willing to help things along, at least for those well connected. And on top of that come government research grants to universities who then spin off companies and keep the profits from the spinoffs.
[1] https://finance.yahoo.com/news/elon-musk-paid-off-teslas-193...
[2] https://www.congress.gov/119/meeting/house/117956/documents/...
[3] https://thehill.com/lobbying/5113500-bottom-line-bezos-blue-...