Sometimes we might suspect people eat recherché foods simply because they're expensive, and they want to show off their wealth or status, or appear sophisitcated. While there's no doubt this happens, sometimes I think reverse snobbery leads us to assume that gourmet food items aren't really any better than regular, plain, honest food (which can, as we all know, be very good). I was definitely brought up with this idea. And watching food fads, we can see that today's prized ingredient is forgotten tomorrow. I remember in the 90's, when balsamic vinegar and extra-virgin olive oil were on everybody's lips.
Some expensive ingredients I have tried have forced me to rethink some of the assumptions I was raised with. They really are better than less-expensive or imitation versions. Or they exist in a category of their own, unmatched by anything else. Here follows a list of a few that spring to mind.
shiitake - These are so complex, earthy, meaty, flinty, and satisfying that the ordinary button mushroom seems like foam rubber.
parmigiano reggiano - This is so good I have known it to single-handedly destroy people's prejudices against gourmet food. I have tasted strawberry flavors in it.
Saint-André - This fairly expensive triple-cream cheese from France, when left out to "ripen" for at least an hour, gives the experience of eating butter, brie, and mushrooms all at the same time. Pair it with a Sauternes or a Vouvray moelleux and you'll have a mystical experience.
Belgian or Swiss chocolate - I don't care what form or brand or flavor this comes in. They say there are chemicals in chocolate that stimulate the brain in the same way that sex does. Apparently the Belgians or Swiss understand this better than we do, because the first time I tasted a Neuhaus chocolate, I was standing, and it so overwhelmed me I actually had to sit down. The flavor blooms in your mouth like a fine aged wine.