One question here obviously concerns doxastic voluntarism (DV). You ask:
"If you know your belief isn't correlated to reality, how can you still believe it?"
Is this a rhetorical question aiming to assert that if you know your belief isn't correlated to reality, you can't still believe it"?
If so, then it just isn't clear that you're right. One possibility is that DV is true (there are, of course, many reasons to believe that it is). And, if DV is true, it's likely that different people have different degrees and kinds of control over their beliefs. After all, people differ with regard to all other known cognitive skills. Some irrational folks simply might have a kind of control over their beliefs that others don't have. That's an empirical question. (Though we normally think that folks who are more rational have greater control over their beliefs.)
You might, however, mean: if you know your belief isn't correlated to reality, you shouldn't still believe it.
That's a normative claim, not an empirical, psychological one. If that's what you mean, then you're in effect expressing surprise that anyone can be that irrational. If so, I guess I'm a little surprised at your surprise. It is a fairly pure case, but it seems to me that it's not that unusual to hear things like this.