Any barrier you can place between you and attackers is a good one. You shedding that barrier is not smart. That goes double in a place like Miami Beach which is becoming a gathering for people who feel they can do pretty much what they want. I have not followed much what is going on down there, but it seems the City Commission is tying the hands of cops in the name of profits. That is a strategy that has been tried before and will backfire.
From what I was able to see in the video, the driver opened the door. It looked like one of the three attackers hit the driver’s door and he took umbrage so he stopped and let the ego make a bet his body paid with interests. The diver could have stayed inside or simply drive away, but chose to confront offenders who touched his vehicle.
And no, even if you had a gun with him, the only thing he would have done is getting at least a charge of assault with a deadly weapon. And here is a good place to remind people who pedestrians have the right of way in Florida in roadways, specially in crosswalks. You may want to check the provisions of Florida Statutes 316.130 to see the latitude they get.
Unchecked Ego will get you in trouble that little recitation about Stupid Places also comes to mind.