Changed his mind about selling the account, after money is already sent.
I offered the seller 150$ USD for that account with PayPal G&S, to which he agreed. Also put 5 USD extra to cover a bit of commission, provided him with a screenshot, how much is that gonna be in euro, to which he agreed. After I already paid, he complained that the amount is a bit small. I offered him to pay 10-15 USD extra to make it better. After that, he entered the account and noticed, that he also had a level 58 boost on it, about which he didnt know, therefore he wants even more money and he wouldn't have agreed if he knew about it being present on the account.
TLDR: Timewaster. After agreeing to a deal and receiving the money, he cancels a deal because now he wants more and has remorse of selling it for too little.