I've never understood this line of thinking. In fact, it feels a bit arbitrary, because your line of thinking can apply to literally anything -- there's no clear cut off point for "useful." By your logic, should we also hold chefs in a low regard. When has their food ever done anything other than make us fat? What about art? Pretty useless. Those people should become engineers and actually contribute something?

you personally don't find a coke to be useful. However, it is a product that brings many people happiness. That actuall seems pretty useful to me.

Further, you completely missed all of the engineering. the modern soda can, the aluminum milling processes, all the high tech tool chains, those happened as a side effect of the mass production of the product you dislike.