I'm very cautious about the personal info I share online, partly because of certain interests I've mentioned (murder and armed robbery) that some other people seem to have an issue with, and also because of the death threats I've received in the past.
There are particular people who have claimed they would like to kill me. While I can't honestly say any of those threats are genuine, there's still a chance that one day someone might just follow through and I have no desire to make myself an easy target should that day ever arrive.
I've also been reported to the police a number of times by people online. Giving my personal info away would make that job a lot easier for the police, should they decide to take action. Of course, I'm not saying the police couldn't track me down easily enough if they wanted to, but without knowing for certain who I am, they would need a warrant to find me through my ISP. At least I assume that's how it works anyway.