Dude, YOU TOOK HIS $10K and took forever to NOT get the job done!!! What the fark are you talking about???
He can't wrap that around his head. He keeps forgetting about the timeline he promised. He makes all his clients sound like they had a change of heart and want their $ back when in reality he failed and fails to deliver and continues to take people's money in hopes of getting out of a hole he can't. That's no business model, that's a joke.
I ran a business at one point and I took a loss of a few thousand dollars on a client when product shipped by the manufacturer was completely off and I had to deliver the product on delivery day. I paid full price for an identical product by buying from a retailer just to make sure the client got what he was supposed to get by the date I had promised. It's not the client's fault or concern the issues you're having with your business. He has paid in good faith and you should deliver the exact product by the date promised. It's called integrity which this guy doesn't have.