As for Cartel's, they are a form of terrorist. They strike fear into those along the border by the violence they carry out. Gangs are terrorists as well. Overall, no matter what the threat, the risk for you, me and everyone else is increased because of Lone Wolf types. If they can carry out a mall attack, sporting event attack, or even detonate an IED or some type of dirty bomb in a concert, they will cause way more harm than the local mugger that might take your wallet or your car.
And if any of those attacks occurs, how do you intend to prepare for them? Hide in your house and not go to a game? Not go to the Mall? Not go out?
None of these things you can prepare except to hide, and then the terrorists have already won.
And why just worry about terrorists? The Russians have escalated flights to intimidate the Balkans. That could escalate and we could be in a shooting war in 24 hours. Better build a fallout bunker. The Rooskies could nuke us.
Again, the best you can do is be aware of your surroundings. Everything else is a false sense of security. but if it makes you feel better, do what you want.