Where Do Burglers Sleep?

My son and I were walking to the playground and we saw one of those Neighborhood Watch signs with a picture of sinister looking person with a red line through it. He asked who that person was and I told him it was a burgler. He asked me what burglers did. I told him they stole things. He didn't really understand why people would steal things, at least not as a profession. To get a better picture of who these people were he asked me where they slept. In houses and apartments like other people, I said. He couldn't reconcile that with these people being so different to us, so to double-check my argument as he always does, he asked me again. Where do buglars sleep? In houses I repeated but I was less sure this time, feeling my argument crumbling. If people live in houses then why do they need to steal things?

Without time to look it up on the web I could not come up with a good answer. Even up looking it up, what I found seemed reasonable for an adult discussion but not straightforward enough for five year olds.