Are you from the USA or in some other country?
Sounds to me like you need to sue Paypal in small claims if they did that to you.
I tried that. The judg tossed out the case. Paypal has a no law sute cluse in there agreement.
In theory Ebay acts as a trusted middle-man between the buyer and seller guaranteeing payment only when goods are confirmed received.
What happens if there's a dispute? The buyer claims the package wasn't received or the goods are partially or fully missing from the package? In a perfect world, there would have been an impartial 3rd party available to inspect the goods at the point of departure and again at the point of reception, so the factual status of the product matches exactly what the buyer is buying.
Unfortunately without that 3rd party, Ebay instead must trust either the buyer or the seller - and they lean much further toward trusting the buyer than the seller. Malicious buyers know this and can exploit buyers simply by opening a dispute, perhaps saying the product received isn't as described in the auction.
"I bought a Titan-2080 video card but the seller shipped me an old GT-560; he ripped me off". Without hard proof, eBay will have the buyer return the "incorrectly-described" product back to the seller and refund their purchase including shipping costs (if they paid).
Meanwhile, the malicious buyer just managed to swap their old video card for a new one; at the cost of a single down-vote and a scathing review from the seller. According to EBay, both sides of the transaction were protected: the buyer was refunded and the seller was returned their product.
As a seller, it's extremely important to choose highly ranked buyers without any of these disputes in their past.