> even if a billionaire does get caught and pays all their back-taxes with penalties, they will still most likely be a billionaire and be able to sustain a pretty posh lifestyle
By that logic, if they just pay their taxes it won't affect their lifestyle either, so their incentive to cheat is also lower.
> the payoff for a billionaire successfully cheating on their taxes is much higher than for a non-billionaire
In absolute terms, sure. And in absolute terms the penalties are much bigger too.
> the IRS prosecutes a lot more low-income people than high-income people (by percentage as well as by absolute numbers) so a billionaire has much better odds of not getting caught
Your conclusion doesn't follow from your evidence. It's possible that low income people are cheating taxes at a higher rate than billionaires. I really don't have a lot of trouble believing this; small tax fraud is widespread, even accepted by a lot of people.
> billionaires have access to better layers, accountants, publicists and politicians to give them negotiating leverage if they do get caught
I don't see any evidence that this guy got a better deal than he should have.
The point of tax enforcement is not to punish billionaires for being billionaires. The point of tax enforcement is to ensure taxes are collected. If you think taxes are too low, or just want to punish billionaires more harshly because they're billionaires, then Congress is the place that has to be changed.