I'm a little surprised at the number of people here that have said "I used to act like X until I bought a gun."
Did you act immature and bought a gun, or did the act of carrying a gun make you grow up? Either way, it sounds like you were still acting irresponsibly when you actually bought the gun.
I learned that being cut off, yelled at, or whatever can be de-escalated by absorbing it - the same way you absorb the barbs of an abusive opponent at the poker table. I grew up in Detroit. It was safe to assume every dickhead was armed, and going for a gun was like chasing outs. If they are already on edge and have a gun, they probably have it more accessible than you. Make one wrong move, and the fastest on the draw will be the only person telling their side of the story to the cops. It doesn't matter who was wrong or who was right if you are dead.
Finally, a firearm is never, ever, a defensive tool. It's an offensive weapon. You're not blocking bullets or punches with a gun, you are taking the offence to your opponent. Avoiding a dangerous situation is defensive. If you are walking to your car with a big win from the casino and are approached with a guy with a gun, he's got the draw on you. There is no way you can draw a gun, aim, disengage the safety, and disable your attacker in less time than it takes him to pull the trigger. That's why police approach a dangerous suspect with their guns out. You simply cannot draw that fast. Forget what you saw in a movie, this is real life. True defence lies in avoiding danger. Ask the casino to hold any big money you win, and withdraw it another day.
Don't act in a way that will only aggravate someone. In short, live life like you never go on tilt.