Well if there is a fire, chances are I'm going to care a whole lot more about other things that I've lost other than my notes.
If it's important enough, I'll transcribe it to an electronic format that is more useful for other people to use. Often I'm taking notes in a very terse format, not writing an entire document. Though often most of the notes I'm taking are ephemeral in nature. I might need those notes for a week a most, not for the next 30 years.
To each their own.