Like a few others on here, I've also been using Ebay for about ten years and have bought literally thousands of items, from nuts and bolts to cars!
A lot of folk still seem wary of using Ebay and there will always be a small few who will try and use it dishonestly. I have only ever had about half a dozen problems, and most of those have been sellers who have supposedly "lost" the item when my winning bid was too low for them, although I never lost money to them. One chap blamed his wife for donating a valuable book to a charity shop on the day before the auction ended!
The one serious problem I had several years ago was when I foolishly agreed to send a bankers draft instead of a cheque or Paypal payment for a very expensive camera from a private seller. The sellers turned out to be a group of scammers using false details that couldn't be traced. After unsuccessfully going through all of Ebays correct procedures, I sent the scammers, via Ebay, an email promising to involve the police and track them down personally. I guess Ebay were concerned about the bad publicity, because they promptly sent me a full refund as a "token of good will"!
You have to remember that an increasing number of sellers on Ebay are genuine long-established merchants who have their own stores, but use Ebay to reach a wider market. Living in a country area as I do, I find it's much easier, quicker and cheaper overall to buy even smaller items such as nuts and bolts, fuses or whatever via Ebay. Most business sellers deliver next day or within two-days at most.
Another advantage is that if I buy a larger item, where delivery isn't available, it gives me an excuse to make the trip in my van and spend a few days in the area!

PS.... don't forget that it is possible the seller in the original post may have just made a genuine mistake!