@JasonVEVO Butlers don't always behave the way you'd like. Drinking coffee instead of sleeping, drinking juice instead of working, not attending to personal hygiene.... (If you're curious, type "sims 3 butler" into a google search field and check out the autofill suggestions.) I think most players have a sense of humor about this, as butlers are sims too, and can be just as unreasonable as the ones we control.
But if this bothers you, you can always make the butler part of your active household. That way, you can redirect his attention when he wanders off or decides to drink twelve cups of coffee instead of going to bed. If you really want an NPC butler but perhaps one that's better at his job, you can move this one into your home and then kick him out. I believe when he moves in, he'll lose his job, and if so he won't get it back when he leaves again. That way, you'll get a different butler the next time you hire one.