It would be wonderful if Xcode could make this issue clear to developers whenever a new version of Xcode is installed, when it prompts the user to install new components.
I was unaware that Xcode was silently hoarding disk space, reported by System Settings > General > Storage only broadly as "System Data", with no other clues.
I spent hours investigating why my disk was nearly full, and then eventually used Xcode > Settings > Components to recover 350 GB (!) of disk space I wasn't using.