You're vastly overrating the network effect, because you left out the considerable damping factor of scammers, criminals, and idiots. I DONT sell on eBay. I nev

You're vastly overrating the network effect, because you left out the considerable damping factor of scammers, criminals, and idiots. I DONT sell on eBay. I never do, because it takes me 10 hours+ just to sell something (re-list 5 times, eliminate 80 spam out of my inbox which is a laborious process, vainly try to notify ebay of a scammer and getting the FAQ thrown at me, get my hopes up 8 times only to be confronted with: Change in plans, please ship to nigeria... and then FINALLY I get a real sale going). I bet there are more people like me. I currently make do with local services like marktplaats.nl which works better for me, but the ability to buy or sell niche materials isn't good. (the network effect applies to idiots/scammers/spammers so there aren't nearly as many). In other words: There's this huge market that basically isn't being served.