You don't understand how Simple Delivery works.
You can't be out of pocket for the postage because you don't pay it.
The buyer pays Ebay.
Ebay send you a label or a QR code and you send the item. You don't pay but use the QR code or the label.
The postage transaction is between the buyer and Ebay. You get paid for your item but Ebay keeps the payment for postage and provides you with the means to send the item.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)