Most TT's remind me of one of the basic laws of parenting. You know, the "bad attention is better than no attention," rule. They don't feel secure enough within themselves, or they feel unnoticed/unappreciated, so they find a way to get the attention they need....and get their own kudos.
I imagine it starts early, and they become pretty good at reading their audiences. They can tell when the story isn't good enough to get the reaction they needed, so they keep adding information (true or not), until reach their goal. They're SO self-centered, that they don't even understand how they've victimized their targets. The target isn't important enough to worry about.
The downside for the victim is that there's usually a tiny shred of truth in the story. So we get called into the boss's office, and are accountable for our mistakes. I mean....everyone makes them....no big deal, right? Then the management starts to lay on the added details, and when you deny, you look like you're just CYA-ing.
IMO....management likes the TT, to a certain extent. They can "bust" the victim, and don't have to look like they're being mean. "Wellll....you know how TT is, right? We'll just ignore this like always. Just be careful, and don't do that thing again."