has a BTC thief ever actually been tracked down and caught before?
Hell yeah.
Trendon T. Shavers
Charlie Shrem
Ross Ulbricht
Neither Charlie nor Ross was caught for stealing. It was money laundering and drug dealing. As far as Trendon, I can't find any proof he was convicted of anything. But he may have.
It's like the first google result. I hope he rots in jail.