This post was persuasively and efficiently articulated, so thank you. A handful of initial reactions:
You seem to have anticipated this response. The definition you begin with—truth as "accurate predictions about our experiences"—is fairly narrow. One could respond that what you identify here are the effects of truth (presumably? but maybe not necessarily), while truth is whatever knowledge enables us to make these predictions. In any case, it doesn't seem self-evident that truth is necessarily concerned with making predictions, and I wonder how much of the argument hinges upon this strict premise. How would it alter if etc.
Relatedly, you say that when we seek truth, "we want to know things that tell us what we’ll find as we experience the world." Rather than primarily aiming to predict in advance what we'll find, might we instead aim to know the things that enable us to understand whatever we actually do find, regardless of whether we expected it (or whether it is as we predicted it would be)? Maybe this knowledge amounts to the same thing in the end. I don't know.
You refer to the thing outside of truth that grounds the quest for it as purpose. Would belief or faith be an acceptable substitute here?
It would seem that [desire for] knowledge of truth already encompasses or takes into account the existence of non-truth-seeking agents and the knowledge requisite to accurately modeling them.
Given your statement in the antepenultimate paragraph—"the reality is that you are not yourself actually a truth-seeking-agent, no matter how much you want it to be so"—this piece ultimately appears to be a reflection on self-knowledge. By encouraging the rigidly truth-obsessed dork to more accurately model non-truth-seeking agents, you are in fact encouraging him to more accurately model himself. So again, the desire for truth (as self-knowledge, or the truth about oneself) still guides the endeavor. (This was the best paragraph in the piece, I think.)
Many thanks for the reply. I realize it may be a tad absurd to question the centrality of prediction, especially given the context of these posts, so I appreciate the judicious responses + links.
Many of the discussions on this site deal in subjects \ frameworks of which I am largely ignorant, so I am here to learn (and have fun). Looking forward to reading your thoughts in the future : )