The question is simple. If Ross William Ulbricht running a darknet market inside a TOR network and he never exits through the exit node, and obviously he won't need to, so how did he get caught?
I was taking a course on the anonymizing techniques and there I had learned through the illustrated examples. As shown below
When a user connects to a TOR so his activity is nonencrypted as shown with a left red arrow it means an ISP can see a user is using a TOR network. Fine. When a user inside a TOR network then his all network is encrypted as shown with green arrow. As soon as, the user leaves the TOR network then his activity becomes again nonencrypted and anyone can see his traffic but not the origin (shown with right red arrow).
In this scenario, when a user enters a TOR network, at the time he is visible to his ISP but if he gets inside the TOR network then he is invisible to the clearnet world. And he can access the .onion services what we call a darknet. So Ross William Ulbricht was running the service inside the darknet and he never needs to leave the TOR network through the exit node to the outside world but yet he caught by the FBI, how?
Here is another example from a famous hacking series MR. Robot season 1 where Elliot tracks the activity of Roni's coffee who was running an illegal website on the darknet so Elliot says if anyone controls the exit node he can take control over the traffic. Again, if Roni was running his services inside the TOR network and did not exit through the exit node of the TOR network so how did Elliot catch him? Obviously, Mr. Robot is not a fake hacking series. 99% of things are real in that series. Here is the youtube reference for that scene. https://www.youtube.com/watch?v=sO2raiSHOhc
So, if not Roni's Coffee owner leave the TOR network nor Ross William Ulbricht then how did they get caught even they were inside the TOR network? How does the exit node plays a srole in both cases?