The last time a bike of ours was stolen, I had left the garage door open while going to the gas station to get fuel for our lawn mower. Came back and it was gone. The worst part is that you question everyone. Every neighbor immediately seems suspect.
I had a fairly expensive mountain bike stolen from my apartment storage unit, which was locked, and the part of the basement where the units were was had a key coded door also. That pissed me off a lot more than if it would've gotten stolen off the street.
The first thing I had stolen of value was a bike I had borrowed. I had no lock for it. Kept it inside. Stopped for a drink at a pub. Parked it where I could see it. Had a couple, bike was there, paid my tab. GONE. In 60 seconds, like I was being watched. Schwinn Collegiate 3 -speed, helluva bike.