You have a radar detector because you expect that you'll probably break the law, but you want to evade penalties.
The morality of that is a separate issue.
I have it because it gives me an extra sense, and who wouldn't want that? I feel blind without it. It is people who track the locations of speed traps who expect they will probably break the law but want to avoid penalties. I just like to know what is going on around me. That van parked on the side of the road? Is that one? My detector tells me if it is. Is there a police car up ahead out of sight? I look around at the traffic and see who is likely to get pinged.
My detector often goes off. Some alerts are false positives, some are real. All of them keep reminding me to check my speed. I am much more aware of it than I used to be. I am a better driver as a result.