I am admittedly not a normal computer user. I don't always fully grasp what's going on deep inside the operating system, nor am I always confident I'm clear on how an application is working with all of the services it requires to function. But I find it interesting, even if just on the most simple, conceptual level.
The majority of computer users want their machines to just work. And though I like seeing how my hardware and software interact, it is preferable to have things just work, so I can get what I need done, and then spend the time I saved doing so leisurely poking at my application's innards. There's an inherent danger in the just works philosophy, however.