It takes something like this to really open your eyes, so don't count on me making the same mistake twice.
I completely understand this feeling. One night I was working alone at the shop on a Supercharge engine swap on my buddies 1987 MR2. I had the front gate closed and locked, and my MR2 was parked within it. I was expecting Marlin to return from out of town around midnight. I remember that it was about 1am and I was inside the engine bay with the hood down relocating the hood latch to install a SC engine lid, had the helmet on and was welding, when I heard the chains on the outter gate rattling. I stopped, listened closely, assumed Marlin was back, and then kept welding, forgetting to even check if Marlin had indeed returned or not.
I ended up so involved in my work, that I didn't even think about "where is Marlin", and around 3am I cleaned up, locked the shop down, and as I was walking out to my car, I noticed that my dome light was on. I thought, "dang that sucks, poor battery" and as I got closer to her, I noticed that my door was ajar! He/they went through the entire cab: Glove Box, pulled stuff out from beneath and behind the seats, and even looked under my floor mats. He stole a $249 Aiwa CD player and a couple CDs. The stupid thing was that I never mounted it firmly, and he could have just removed two simple phillips screws, but instead decided to prybar the entire dash and I ended up replacing almost everything.
It must have been the next day that I purchased and installed a $99 alarm system from The Good Guys. Never had any trouble since.
BigMike