To be fair, exactly this happened to a friend of mine living in Fulham, London. His laptop (a very pricey MacBook) was visible through the window from the street. Someone was in through the (old, poorly-secured) window and back out with the laptop within a couple of minutes whilst my friend was in the shop across the street. Didn't check the bedroom for jewelry, didn't take his expensive decks or TV - just grabbed the laptop and left. It seems some thieves do specialise - either that, or my mate is into some other stuff I don't know about and had just been told he was going to receive an encrypted file...hmmm.

They may have heard a sound, assume they may be about to be discovered, and just scarpered with what the already had in their hands (which just happened to be the laptop).

My car was broken into a few years back and all the thief took was my school books sitting in the back seat. My iPod was even sitting in the cup holder on a pile of loose change.