Also, billionaires obviously don't make their money from a job like the middle class do — who then pay income tax.
Billionaires just move money around to where they want it to work for them.
Musk is an example of someone who has done well with the hundreds of millions he made selling paypal to ebay.
It's a good thing the government didn't take like 70-90% of his profits (like they did before JFK) — Musk wouldn't have been able to start his great new companies.