Someone bought the PS4 I was selling on ebay so I shipped a rock to him
Why would you send him a rock instead?
I had to do something, what else could I do?
It is a crime to steal someone's money and send a fake item. You should give them a refund and apologize before you get banned from selling.
Fine I will refund, but I will not apologize.
Well at least you are going to refund it. Next time just send the person the item that they purchased.