Sigh.
What you consider to be "stupid, misinformed, has a changing and unpredictable taste" doesn't matter, all that matters is that the decision makes sense to the individuals themselves. You don't have to agree with it or understand it, only that the decision is what's preferred by that person's innate preference/utility function.
You people really need to actually study what this stuff is actually talking about because criticizing it.
https://plato.stanford.edu/entries/decision-theory/
https://www.amazon.com/Introduction-Decision-Cambridge-Introductions-Philosophy/dp/0521716543
The axioms underlying the models and theories are very simple and intuitive, stuff like "if you prefer A to B, and B to C, then you prefer A over C".
You'll need at least a little probability and a little game theory.
I haven't read this textbook, but it seems pretty good: https://www.amazon.com/Introduction-Decision-Cambridge-Introductions-Philosophy/dp/0521716543