The answer is there is no legitimate reason why this happens.
The answer is the youth gangs another assorted criminal types do things like this. Sometimes they can make money dealing in stolen merchandise, and sometimes they do vandalism just for the hell of it. These types of people do not do productive things in their lives, so instead they do destructive things.
Their thought process is beyond the frame of reference of many of us . There is no legitimate reason to do these things that they do.
You just described the Democratic Party to a tee—they are evil because they are evil—no need to dig deeper.
This is why every law-abiding citizen should be deputized and equipped with devices that shoot to hurt like hell. Let the thives, taggers, and vandals feel some immediate pain.