"I get screwed by the man so it is ok for me to screw other people" - what are your thoughts on this mindset?

Another question made me think of this. I often hear people justifying their behavior (my ex-husband among them) based on the fact that they have been mistreated by others. They are justified in taking office supplies from work because their employer takes advantage of them. They are justified tossing their trash out the window of their car because they are forced to pay city taxes. These are the folks who can justify almost any misbehavior based on the mistreatment they have endured and of course they perceive anything that doesn’t go their way as a purposeful mistreatment. What is your take on this mindset?