[zanny]

Wealth inequality is the perfect example. It is in the best interests of society to keep inequality under control - extreme inequality, like we have today, has negative social and economic implications. But if you are on top, with all the money in the world, why would you ever voluntarily give your money away?

Like the other response said, its prisoners dilemma. It is in the best interests of the rich to pay for honestly a majority stake in the society because they are the ones prospering the most from it. But if any one person of the ownership class can avoid paying, they have an incredible competitive advantage over their peers they will obviously exploit.

Independently, it is never in your best interests to give your money away in taxes. It is always in your best interests to have everyone else pay them but you.

This is why you cannot test any number of policies - basic income, progressive taxation, universal healthcare, amongst many more - because if you are not getting more out of these policies than you put in you have the instant ability to flee from paying for them.