Wrong on both counts - drug addiction harms anybody connected with the user, and sexual abuse behaviors harm the behaver, just in much less obvious ways. This is the exact kind of rationalization people create to deny reality.
edit: Every single response to this comment is "they aren't the same thing" because drug abusers only harm themselves and sexual predators only harm others. Wrong on both counts. Drug addition hurts everyone involved with the addict, and any kind of violence hurts the attacker, just in different and much less obvious ways. Instead of trying to rationalize refusing to help perpetrators get over being the way they are - because doing that would just make you complicit, and you crave vengeance! - maybe try to get over seeing everything as a binary choice between good and evil.