I sort of agree with you. Note that it's the people who think highly of their probably nice cars who when something bad happens say that the person who did it must have been jealous, if something happened to my old VB when I had it I know for a fact no one would be jealous of my sick 15" trispokes or VH front end
If you see a dint in your car at the carpark it's not necessarily some jealous Ford fan (they don't like Holden to begin with so why would they be jealous?), it could just be a badly disciplined kid opening the door all the way and a parent who doesn't care/doesn't want to pay to fix it so they leave quick smart.
If your car gets stolen it's likely not because they were jealous, they saw it as being or containing things which are valuable. They're probably junkies looking for a fix, and would end up selling the stuff, not keeping it.
If you are a show-off then people probably aren't jealous of you, they just think you're a tool and might say something.
Of coarse this isn't to say there aren't jealous people in the world, there will be of coarse but of the amount of people who are jealous it would take an even smaller minority to say or do something stupid. I think people need to see the reasons why things are rather than straight away assuming it was jealousy.