6
A private island
Offered several times. Won at least twice. Kept approximately never.
Island giveaways have been run by tourism boards, rum brands and at least one newspaper. The prize is usually a small, undeveloped island or a long lease on one.
The problem is the same one every time. An island has no power, no water, no road and no shop, and a winner on an ordinary income now owns an asset with running costs and a tax bill and no way to visit it cheaply.
Most winners sell. The ones who did not tend to have been wealthy already, which rather defeats the romance of the thing.
The tax position is the part that catches people. An island awarded as a prize is income at its assessed value, payable that year, and an asset that is hard to value is also hard to sell quickly at that value. More than one winner has discovered that the tax bill arrives faster than a buyer does.