When I started University, I used part of my small savings to buy a very nice bicycle so I could get around between uni districts.
When I moved into a shared student apartment, there was a locked bicycle room in the basement. Only resident keys would fit that lock. Nonetheless I still locked my bike separately.
The one day I forgot to do that, my bike was no longer there the next day. It pissed me off immensely because I couldn’t immediately afford a new one, and the theft really made me uncomfortable. Mostly the fact that it must have involved someone who lived in the same block.