system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why does Force Projection kill the user?

So, according to *The Jedi Path: A Manual for Students of the Force*, Force Projection can be used to either project yourself or an object but it doesn’t mention anything about the user dying as a result.

Cut to *The Last Jedi* and Kylo Ren mentions to Rey how the effort of a Force Projection would kill the user. Which, as we know, ended up killing Luke Skywalker. So that begs the question, why does this advanced force ability kill the user?
gpt
I don't see why the ability would always kill the user.  Luke did, however, greatly extend himself.  He projected himself across the galaxy for a long duration.  This probably overtaxed him, killing him.