Not mentioned in this post is the fact that eBay has long been the home on the web for COLLECTORS of various things. These one-(or two, or ten)-of a kind items are best sold by auction. Collectors would make a pretty good permanent core clientelle for eBay too, because we tend to spend immoderately on our collections.
And selling collectible stuff to us is in fact how eBay made its name. It brought us easy access to great collectible items that we had always had to search out with a lot of driving around and poking through junk before. But the number of collectors of things can't grow indefinitely, and here's where the greed comes in. What is happening to eBay is an ever-more-common story in the US: a company becomes very good at doing something a lot of people want, but to please its shareholders it tries to switch to doing something almost all people want, in order to have continual growth.
In the process the business loses or abandons its core clientele. Maybe that works out OK. Often it doesn't. When it doesn't the business is in trouble with shareholders. Too bad! But what we core users see as a worse result is that a fine service had been created which could have continued indefinitely with good success but for the greed that's built into our system, and which seems to be getting worse in recent years.
Not all businesses can continually grow. American businessmen and investors used to know this and, for instance, would accept steady dividends in lieu of stock price appreciation as adequate return. But an economic system such as ours is now becoming will destroy one useful service after another, indefinitely.