I already knew people wanted to sell the stuff in their attic or send money to other people before eBay or PayPal came along, because the offline world had already invented garage sales and Western Union.
This has no offline corollary and is economically empowering to so many people. 5. eBay and reallocating existing goods. eBay is actually a little like direct trade.
This works toward maximizing the utility that item can bring to someone. eBay is not alone in this regard.