IDK, it opens the world up to some fucked up mechanics. Like, I assume the measure of $1B isn't cash, or else a lot of billionaires wouldn't explode since it's all stocks. So in that case it's just the worth of your assets.
So what stops two $500M people from assassinating good people just by offering to make a joint purchase of that person's right shoe for $1B? That would mean the right shoe of the good person is now worth $1B and they explode. It's basically Death Note on steroids at this point.