And yes, it continues to happen:

Bitcoin buyer robbed of RM1mil in cash
- https://www.thestar.com.my/news/nation/2018/04/13/bitcoin-buyer-robbed-of-rm1mil-in-cash

Heh, "A police spokesman told the Straits Times that they were also investigating the origins of [buyer]'s money, which he carried in cash."

And though no violence was involved, here's a very large deal where the buyer almost got scammed:

How an OTC Bitcoin Scammer Almost Stole $600 Million
- https://news.bitcoin.com/how-an-otc-bitcoin-scammer-almost-stole-600-million

Bitcoin ATM hit ... thieves assault cashier with bear spray, then pull the cash trays from the Bitcoin ATM (Chevron Gas Station Irving, TX)
- https://www.youtube.com/watch?v=lbImdks9gkM

"The gang used the office to lure the two brothers to come to the office to sell them the Bitcoin."
- https://gulfnews.com/news/uae/crime/watch-dubai-police-recovers-dh7m-from-bitcoin-heist-1.2213314