A few months ago, Ebay made a change to the offer system.
A seller could send offers to buyers as usual, but when a buyer accepted an offer (or made an offer and the seller accepted it), it wasn't final until the buyer paid.
So, another buyer could also make an offer, get it accepted, pay more quickly and win 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)