Based on a 5 year national average the lifetime victimization rate for violent crime in the United States is about 40%, meaning that you have about a 40% of being the victim of aggregated assault, armed robbery, or sexual assault at least once in your lifetime.

With that you have two options, your first option is to do nothing and hope you're in the 60% that's never victimized, or if you're unlucky enough to find yourself in that 40% you forfeit and hope you can live with the consequences.

The other option is to make preparations beforehand as to minimize the consequences if you're in that 40%. That's not to say that it's all a guarantee, you can still lose, but probabilities of a positive outcome go up significantly when the victim is both armed & competent. The downside is preparation has a significant cost attached in terms of both time & money, which is all a waste in hindsight if you find yourself in that 60%.

We make these sorts of decisions all the time. Never attending a first aid class is free and requires zero effort, but if grandma happens to have a heart attack at Christmas dinner you have no ability to influence the outcome. On the other hand you can spend your entire life investing in a 401k to die in you 50s and never actually use that money. So it's ultimately up to you to decide what sort of risks you're willing to take...