We could start FI-Ville - a closed community - somewhere far far away from the rat-racers with half a billion. In Switzerland we sometimes have rich people negotiating their own tax laws with farmer villages. Switzerland is a highly democratic place where small communes decide themselves how much to tax their residents. Let’s assume the typical farmer village with 200 people. Maybe 50 of them working, grossing a total of $50,000 per head, that’s a total income of $2,500,000 for the village. Let’s further assume they tax about 20% which will give the commune a budget of CHF 500,000 per year. Now, let’s further assume you are Michael Schumacher or Tina Turner (we sometimes call them tax-fugitives) and you plan to move to our little farmer village. Before you settle, you may join the townhall meeting and negotiate your own tax-rate or a flat-tax with the guys yourself! If your annual income exceeds CHF 500,000 you can actually walk up to the governing body (usually a committee of part-time politicians) and show them how your fixed contribution of $100,000 per year could help them lowering their own tax rate from 20% to 16% (e.g. you pay $100,000 of their $500,000 budget, lowering their share to $400,000 or 16% of $2,500,000). The townhall will most likely agree to your proposal!
Next thing you know, your wealthy friend comes to visit you in your new home and decides to purchase the land parcel next to yours. He walks up to the townhall with the same proposal and caboom, the villagers only need to come up with $300,000 of their $500,000 budget - the tax has been lowered to single digit territory. Now, assume FI-Ville. Haha, great idea. Would be possible over here!