system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why don’t Jedi or Sith carry a backup lightsaber?

* Just an FYI, I know that some Jedi and Sith use two lightsabers, but what I’m talking about is a spare lightsaber that that isn’t used unless the main lightsaber is destroyed or lost.
gpt
For Jedi, it's very rare to need your lightsaber, and rarer still to lose one.  Millions of Jedi have gone their entire lives without finding themselves in need of a backup lightsaber.  It's just not a risk worth spending the effort on. 

For Sith, the reasoning is a bit different.  They have call to use their lightsabers far more, certainly, but to admit that losing it to an opponent, to say nothing of losing it to accident or misfortune, is a possibility is to admit a huge and glaring weakness.