Actually, the reality is, no one gets rich by sheer hard work though focus definitely can play a part. What happens with billionaires is the work is in making the seed if at all, or acquiring that seed from generational wealth, good fortune, or exploitation of others. Once the seed starts to germinate it produces the wealth, and if nurtured it reaches a self sustaining point where it cannot stop generating more.
I challenge you heisenberg, master of uncertainty, to name me a billionaire who works as hard as a day labourer, or a cleaner, or a miner or a nurse or teacher. I also challenge you to explain to me why that billionaire should not pay at exactly the same income tax rate as one of those blessed ordinary folk, if your premise that their income is also derived from hard work and focus is true.
Fact is, billionaires do not pay fair taxes when they are compared to the regime imposed upon the bloke who empties your rubbish bins, or the woman who stands at the checkout at your local supermarket.
The really silly thing though about this state of affairs, is that if that billionaire did pay tax on the income at that rate, they wouldn't even notice it. The community they live in though, most certainly would...