so apart from less weight wtf do you get for more money?
Materials, manufacturing tolerance/process, exclusivity, perception etc etc.
look at this way, all groupset manufacturers have a range of products that match depth of pockets, now, it may very well be the case that Deore will perform (in most places) almost indistinguishably from XTR, but if Shimano priced XTR anywhere near Deore, they’d devalue the entire brand. XTR is the best, ergo it has to cost the most. It follows then that XTR sets the benchmark for the start of top end products, thusly to make the claim that something is “better” than XTR it has to cost more.
As long as the punter’s happy, wors, you don’t have to worry about it, OK?