Yes your penultimate paragraph is my core point. I argue that’s the real standard. Freedom means different things to different people. If you try to define it objectively, you quickly are in the realm of ideology and then wondering why half of the country reject such ideology, while describing their behavior as “against their interest.”
The Mullah regime in Iran also tries to forcefully direct people to heaven, because they think that’s in their best interest long term and they don’t know better. In fact they sometimes even use the same phrases used in your analogy to refer to mortal life: a prison.
It's great that you two were able to come to an understanding & all, but your agreement leads me to wonder if many voters choose to fixate on culture war issues in an attempt to distract from real quality of life problems that seem impossible to fix and thus just better to accept.
This is extremely close to one of the early "OK, but maybe there's a reason what we're observing at the individual level isn't so scary" hypotheses explored by political science in the latter half of the 20th century—that individually poor choices would nonetheless produce good outcomes by being in some way chaotic and the good outcomes often manifesting as attractors in that chaotic space, or something like that, or by some "wisdom of the crowds" effect that emerges in aggregate. These approaches have been found untenable despite much trying, though I think there are some limited efforts at it still under way.
HOWEVER! I think after this post I do see what you're actually getting at, which is that if people believe they voted in their own best interests ("as they see it" being key) then they may believe they did in-fact do that indefinitely, even if entirely incorrect, so long as they... well, continue to believe so.
The prisoner voting to remain a prisoner not because they don't want to be free—not because if you describe completely and in detail, leaving nothing out, the conditions they're in-fact in they tell you they would love to live that way (they claim they would hate it!), and then if you also describe free life they claim that is the outcome they would rather have, and if you carefully probe you find that it's not even for some greater-interest purpose they are voting to remain imprisoned (it's not that they believe they'd be a danger to others if free, for example), but because they believe they aren't in prison despite [gestures at their prison cell]—is voting in their own interest.
By that standard, yes, a lot more voters are voting in their own interest than may be reckoned by other standards.