IT isn't "overhead", it's what keeps modern businesses running. If an IT dept. is being treated as overhead or janitors, that means that business is just treading water on existing tech and is failing to take advantage of new capabilities. If you're in IT and being treated like a janitor, you probably don't want to invest in the company stock plan.
OTOH, I've also run into some IT departments where the development teams think they are gods and treat the test teams and operations teams with the same condescension that comes from PHBs. "Teamwork" is such an inane term, but if you don't treat your co-workers with respect (at least outside of your inner thoughts) it has an erosive effect on your company's success. This applies both to the IT user who f-s up their computer AND to the guy who has to deal with that user both to fix the immediate issue and (with luck) educate the user just enough to prevent future disasters.