I think we need to clarify whether we are talking about the film or book. I cannot speak with any great knowledge on the film's mythology yet because only so much has been shown. In regards to the book, I think it is pretty clear that while It maintains its personal killing ground, the personal damnation and corruption of the people in isn't really of much interest to it.
Been a long time since I read the book but I'm sure there's a time in one of the interludes that Mike ponders whether the relationship between It and Derry is symbiotic. Have to look it up.