I mostly sell digital items, and that means that there is no need for physical shipping and tracking.

A buyer on the 28th of April bought multiple digital items from me, then after I delivered it, he opened payment disputes for all of it, and the reason "buyer did not recognize the transaction". That is just plain stupidity, the buyer said "thanks" in the EBAY CHAT after I delivered it, which means he acknowledges that the transaction was valid.  I submitted all relevant information including date, name, order ID, and the item itself on the day the dispute was opened. 

Then today I received the outcome for all the payment disputes, and of course no surprise, he won ALL FRICKIN FIVE. 

Recently I also got another dispute for $300 USD digital item, for the same reason. 

I know it's part of business to lose money to these greedy and abusive buyers, but can anyone give me some advice how to avoid these people? I am starting to lose it, have already lost hundreds of dollars to these people for absolutely no reason.