why I should pay fees for selling
You don’t pay fees for selling you pay fees for protection.
Don’t forget the seller needs protection also.
My friend recently had someone chargeback scam him on his PS3. Luckily he use paypal properly AND had tracking information, and PayPal was on his side.
(He was the seller. The buyer tried to chargeback scam him – you can google that to arm yourselves against it, fairly common scam.)