Nope, don't think you're paranoid. It's just a sign of the times.
Some people in todays society just don't give a hoot about other peoples property, personal space, or even just common courtesies that used to be extened to strangers 10-20 years ago. They just think what ever they want they can just take. I can't even let my kids out in the driveway with out having to worry about some pedophile scooping one of them up!
(Sorry, just a peeve of mine!
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Being cautious is what keeps you out of trouble, makes you lock the car/house door when you leave, and gives you the safeguard and peace of mind that you did what you had to do to protect yourself from others who may do ill will to you. After that, there's not much else you can do.
It doesn't hurt to take precautions. Can you lock you car in a garage or is it in the open in an alley? Even though my car's only a '72 when I go out on vacations and such I always park another car in front of it in the driveway to make it that much harder to get to my car just for my peace of mind. Never know, there might be a hot market for '72 Challengers someday!
You could buy a clunker for a couple hundred bucks that moves and park it such that it can block others from getting to your car and so that the clunker can't be towed away that easily, like perpedicular to the way a ramp truck might try to take your car away. (sorry, don't know how wide the alley is.)
But that would be cool if that was Chip Foose.....