For me at least I do all of my development on the command line, so it's just much easier to use the git CLI instead of switching between applications. And regardless, basically all the commands I run (moving between commits and rebasing, mainly) can be done just as fast or faster with the CLI, with the added benefit of being able to see and retrieve your command history to easily redo actions.

I kind of have the opposite question - what benefit does a GUI have for git? If your tree gets super complex I get how a GUI makes it easier to navigate, but if you only have a couple branches it seems easy enough to just view in terminal.