They could also commit to giving 10% of their personal income or 2.5% of the value of their ne worth (whichever is greater) to the most effective charities now, while they’re waiting for the taxes to come.

Chris Anderson (of TED) has suggested this and had the math run, and worked out if every ultra wealthy person on record in the world did this it would generate enough money solve basically all pressing concerns to do with poverty and climate many times over (so we don’t even need all of them).

It’s never going to happen though, because Chris hasn’t accounted for the fact that most people who acquire wealth to this degree are some degree of sociopathic or at the very least believe somehow they’re entitled to be as wealthy as they are. So we need government regulation. Problem is we need it everywhere all at once, or these people just move their wealth around which can still severely damage the economy. But some countries, especially smaller ones, need to be brave. Europe taxes their wealthy reasonably well, and it’s clear it makes living in those nations better. More need to lead by example.