And this is the problem. There isn't a good answer for the victim, at the time. You are unlikely to be in a position to effectively defend yourself, even if you have a gun. The better concealed the gun is, the longer it takes to pull, and the better the response time with the pull, the more likely the thief is to know you have it and act on that knowledge.

This is why anyone not bullshitting you tells you to do the thing that is least likely to get you killed, and that is just peacefully hand over the stuff, and let them go, then call the cops, and let them do nothing. The real way to reduce crime is to fix systemic ills.