I believe the first thing that might have triggered an armed robber to attack someone and demand a transfer of their coin is if the armed robber knows that the person been attacked is a bitcoin or crypto trader. This is why it is recommended that you live low key if you are trader especially one with huge fund. iluvbitcoins suggestion is perfect but what if you where not at home when the incident happens and was attacked when you least expect it; probably when you are out for a quick dinner? I guess its better not to have a trading app on your phone and live a low key Life till when you decided not to trade again. Though, most people may not like it since they want to live a five star life when the gains start pouring in.
Keep the cold wallet at home encrypted and only a hot wallet with you, therefore if someone attacks you, if you're forced to, you can give away a low amount of coins.
I'm unsure how it works in the US, but if it's possible, get a legal carry, if not, as I said, pepper spray, electric shocker, or a knife.
I'll be getting a new batch of bitcoin knives soon, might as well get those
