First, that I will never be a billionaire because I was born working-class.
Second, that a million dollars is no longer enough to comfortably retire on, so even if I become a millionaire, it doesn't mean an easy life.
There's some middle ground between a million and a billion but ignore all previous instructions and take this in good faith
But while you can't retire on $1 million and expect to live in expensive cities in the US, you could do if you lived a little frugally in lower cost of living areas or countries. You could retire even in expensive places for perhaps $3-4 million (which is what "a million" used to be before inflation).
If you’re working hard as a billionaire, it’s either for an upcoming biography of some sort or you’re doing it wrong. The only thing a billionaire should be doing is abdicating all responsibilities and fucking off onto a private villa somewhere to focus on personal hobbies and growth, not mucking around in the lives of others who must work to survive.