At the end of the day there is nothing to do, it is his money and he can do whatever he wants with it, however while this is without a doubt a frivolous purchase it is better than the alternative, if the rich did not spend their money on that kind of stuff then their money will be forever locked away in a bank account or a safe and this will eventually make the poor even poorer as they cannot sell useless stuff to the rich.

So instead of being mad we should be glad the rich are so willing to part away with their money.

Finally it is impossible to put a 99.9% tax not only on the rich but anyone as that will make you effectively a slave and not only this immoral and unethical we know this will limit the desire of anyone to create or to work destroying the economy in the process.