Can't imagine a scenario in which a person avoided using Wikipedia all their life till now just because things looked a bit brighter on screen.
Dark mode makes things easier for its existing userbase (practically anyone with an internet wanting to learn) but that's that
That's true, it will make things easier for the current users. But as I said, I doubt if it will increase the overall hits for Wikipedia or be a last straw for people hesitating to use the site