My experience having an advisor wasn't quite either of those.
I was certainly working on his research, but he wasn't trying to keep me around as long as possible. He also didn't want me gone as soon as possible.
He seemed to have something he was trying to teach me, and I dare say I learned a few things, but I'm still not sure if they were the things he intended me to learn. He would often directly articulate things, but they weren't learnable or understandable principles, just sort of... mottoes. Things like, "Look. At. The data."
The whole thing taught me the most about how many ways there are for noise and human error to creep into an experiment, and how very much prior knowledge and information you actually need just to be sure that your data is at all real in the first place. It also combined with my exposure to LW-y stuff to spark an interest in machine learning and statistics. Oh, and I learned a lot about the importance of using very nice Latex to make papers look properly professional.
Adviser's mission accomplished? Fuck if I know, but I did still manage to pass a thesis defense (on what I think was sheer politics: my manuscript was quite unpolished, but nobody wanted to speak the impolitic fact that I should have had more guidance in certain aspects before submitting, so I passed with an entirely acceptable grade nonetheless).
Among my friends interested in rationality, effective altruism, and existential risk reduction, I often hear: "If you want to have a real positive impact on the world, grad school is a waste of time. It's better to use deliberate practice to learn whatever you need instead of working within the confines of an institution."
While I'd agree that grad school will not make you do good for the world, if you're a self-driven person who can spend time in a PhD program deliberately acquiring skills and connections for making a positive difference, I think you can make grad school a highly productive path, perhaps more so than many alternatives. In this post, I want to share some advice that I've been repeating a lot lately for how to do this:
That's all I have for now. The main sentiment behind most of this, I think, is that you have to be deliberate to get the most out of a PhD program, rather than passively expecting it to make you into anything in particular. Grad school still isn't for everyone, and far from it. But if you were seriously considering it at some point, and "do something more useful" felt like a compelling reason not to go, be sure to first consider the most useful version of grad that you could reliably make for yourself... and then decide whether or not to do it.
Please email me (lastname@thisdomain.com) if you have more ideas for getting the most out of grad school!