I used eBay for years buying everything from computers to expensive bikes. I even helped a friend who bought a car from eBay.

Now? Full of knock offs and scams. My last transactions were garbage designed to last long enough for a product photo shoot. Using any of these products for their intended purpose is a real safety risk and returns require a back and forth with automated systems designed to try to make you give up before you get any $$ back.

I haven't used eBay in ~8 and likely never will again. The thing about critical mass and network effect is it has as much (if not more) of an impact during a service's decline.