Well Guan, if you have just had your hair blow-dried at the salon, or wearing your new leather jacket, then yes, rain can be ‘costly’ sans umbrella. But is it ‘expensive’?
If you are an ice-cream vendor, I guess rainy days mean less people out there to buy your ice-cream. But that’s a ‘loss of income’, not costly nor expensive. Or if you’re Djokovic, it might be raining on the day that you’re feeling ‘in the game’ and ready to win the cup, but that is a ‘loss of opportunity’.
What is ‘expensive’ anyway? Expensive implies paying, not losing – and paying much, much more than what you would normally pay. Another way of looking at it is that the sellers are extracting all they could from your consumer surplus.
I don’t think umbrellas are sold with surge-pricing in mind, or maybe I’m wrong. Maybe they are really sold downpour-priced, who knows? And is ‘saving for a rainy day’ even has anything to do with umbrellas?
I don’t know where ‘saving for a rainy day’ came from, Guan. I think you’re right, what is it really that we’re saving for on rainy days? Maybe you should ask Uber.