I don't know if that was their fatal error, but it was one of many bone-headed mistakes. Like directing their users to access the site through onion.to, which thankfully never did anything malicious but could have been an MITM proxy that stole people's account credentials like those Atlantis phishing sites. Or suggesting CryptoCat as a place to chat with reporters, when CryptoCat's encryption was broken up until a couple of months ago (why not use an in-house messaging system that you can control and secure rather than a third party service with a long history of security vulnerabilities?). Or the lack of a tumbler (how were coins transferred safely from buyers to sellers?). Or their media blitz, which brought way more unwanted attention on them than they needed, especially considering their size. The real reason for the shut down may be far more mundane than these speculations about security problems, though. Quite simply, they weren't profitable so they closed their business. They may have planned it all along. If the media blitz didn't bring in enough customers, they were going to quit. It was a hail mary and it didn't work. They got a decent number of sign ups, or so they claimed, but that didn't convert to sales, as is demonstrated by the fact that most listings have no reviews. The reason the media blitz didn't work and they lost in the competition against SR is not because of any security issues, since most people don't know anything about those issues and that was not a part of their decision making process. They lost because they couldn't beat the network effect on SR. How likely is Facebook to be replaced by another social network at this point? Any new social network will be a wasteland. If you sign up, you will have no friends there. But if you sign up on Facebook, half the people you know will already by on it, creating a better experience. SR's biggest asset is the people who are already using it. A new buyer can get instant access to 1200+ vendors, while a new vendor can get instant access to tens of thousands of buyers. Another aspect of it is the psychology of brand loyalty. SR has proven to be a trusted platform. People like and trust DPR (they don't merely put up him like Mark Zuckerberg, for example). People are rightfully suspicious of others in the drug world, because there are a lot of scammers and assholes, but SR works for the vast majority of people. It has proven itself. People stick with what works, rather than take risks with new products (or markets) even if they are theoretically a better alternative.