"Only once in four years did a university security guard ask me to take it outside and lock it up. I asked why and he said: "university policy doesn't allow bikes in the building." I responded that it wasn't a bike. It was a frame and would only be a bike when assembled with wheels which it wasn't when in the building."
wow.
There you have it. Your "I've never had to lock my bike up up outside" system is really "I can only cycle to places where I know I can take my bike inside". That doesn't sound like much of a way to live a life to me.
Like your bike? Only ride it during the day, store it in your apartment next to your purse and credit card. Don't use it to meet with friends for a night out. Don't take it to get to the movies. Think hard if you plan to stroll through the city for an hour.
Ideally, you drive around in a circle, get back home and .. carry it N floors, storing it safely in your apartment again.
I really believe that this is the only way to keep a bike. Which is the reason why I don't keep a bike anymore. It's just not feasible to have (a decent) one.