I'd tell them what a pathetic excuse for a human being I am and if they want to end up being it, keep the way they're going.

Nothing to do with money though because half the world would write themselves the winning lottery numbers and stock exchange highs and lows, so it wouldn't work.
And I'd only write them a letter if I was
really desperate! 'Cause then that butterfly effect thing would work and any consequence would be better than the sorry state I'd be in.
Sorry, not in a serious mood today.
