Hrm... I personally am curious about stuff. I have a "I want to know... just because." for various things. A clever and elegant mathematical trick/derivation/proof "feels like" a good joke, in the sense that I seem to experience similar types of pleasure from both, in some ways. At least sometimes.

So for me, personally, it'd be a terminal value in addition to being an instrumental value. It certainly isn't my ONLY (apparently) terminal value, but it's one of them.