Why is refined oil cheaper than cold press oil?
Your assumption is unfortunately too simplified. There are a lot of factors at play that you haven't considered so far:
Let’s look at unrefined oils first:
For them to be marketable, they must be free of off-flavors and overall of a higher quality than what goes into the production of refined oils. The yield is typically lower and production processes (e.g. cold press) can be more complicated and thus more expensive. Their shelf life is significantly shorter, which is also a cost factor, as producers and resellers can store their stock for only a limited time.
Refined oils may be "less nutritious", but for many applications that’s irrelevant or even counter-indicative. Refined oils typically have a significantly higher smoke point (which is a use case where your "good" unrefined oils turn "bad" very quickly), so they are more suitable for high-heat uses like frying. While the refining is an extra step in the production process, you can make refined oils with a higher yield, faster processing and higher tolerance with regards to the input, which overall is typically cheaper. The resulting relatively neutral flavor makes refined oils way more versatile (your probably don’t want your fries to taste like coconut) for those applications where you need an oil, but not a prominent flavor.
In short, you want probably both kinds in your kitchen - the refined as the workhorse for frying and cooking, robust, cheap and heat-tolerant, the unrefined to add flavor to your dishes either during gentle cooking or added at the end, some oils are specifically used more like a flavor garnish, e.g. pumpkin seed oil.
Supplimental answer:
Refined oils are often made from materials that couldn't or wouldn't be used in cold pressed oils, which leads to lower input costs and increased yields.
For example, refined olive oil will contain olive pomace oil (the additional oil from the pits and skins), as well as cheap nut oils and even soybean oil that has been filtered, deoderized, and treated to look like olive oil. The cheapness of the ingredients far outweighs the cost of the chemical processing.
The same is true of vegetable oils, to a lesser degree. Yes, refined rapeseed oil requires more processing, but the yield from the same crop is four or more times greater.
There are a few oils, such as sunflower, where "pure refined" versions are available. That is, high-quality cold-pressed oil is filtered to remove impurities and raise the smoke point. You'll find that these oils are not cheaper than their unrefined counterparts.
personally, I prefer cold pressed "virgin" oils because they're pure, no contamination with other products (I have rather serious food allergies for many seed oils, virgin oils tend to have a legal requirement to not contain those as additives). The stronger flavour and generally lower smoke point however limit their usefulness in some situations, restricting my choices of food preparation method.
Speaking of olive oil (what I know :-), refined oil is cheaper because it's a sub-product of cold pressed oil.
After you get your EVOO, in the presses you have what in Italy is called "sansa": skins, broken kernels, smashed pulp.
Sansa is processed first with steam to extract a first fraction of residual oil ("olio di sansa", that is regulated by law) that requires refining, because the more aggressive extraction process brings in extraneous, annoying flavors, then with chemical solvents to extract the remaining fraction (usually sold as lighting oil, not allowed for human consumption); alternatively, the 3rd phase material can be used to improve animal food.
I think that similar procedures are applied to different oil types if the cold press variety has a pronounced market appeal, otherwise all the oil produced is of the refined type, as the yield is much higher when you extract using heat and/or solvents, not just mechanical procedures.
