I have a friend who is highly -- what Americans call "cheap", and Brits, "mean" (and he's always had very well-paying jobs). He's a byword among his friends and family, for his extreme cheapskate-ishness. (He does also have some excellent qualities.)
Many instances of petty penny-pinching on his part over the years, come to mind. One IMO egregious one which sticks with me, is: I was staying at his home one time, and was making coffee for him, me, and I think another visitor. I put in the kettle, well over the necessary amount of water for three cups of coffee, and boiled it. Friend, finding the surplus hot water, insisted in putting it into a thermos flask to keep it hot until a future occasion when hot water would be wanted.
I can "see with my head", the point of trying to measure out the approximate amount of water that you'll need to boil -- though I'm just not capable of functioning that way; but the thermos-flask stunt, frankly struck me as -- to put it mildly, over-the-top.
I used to work for 2 brothers who were millionaires many times over. They were obsessed with stamps. Everyday they would check the incoming mail to see if any stamps had accidentally not been cancelled and then they would spend hours carefully steaming and soaking off the stamps for reuse. They got very upset at me one day when I let a stamp get past me.
My cheapskate friend is just the same with the business of soaking off and reusing accidentally-unfranked stamps -- he does it "religiously". The one time I tried to do the same thing: I somehow did not manage to glue the stamp successfully, to the envelope -- it clearly got detached in transit: I was told by the recipient of that letter, that I had forgotten to stamp it, and he had had to pay postage due. (I duly explained to him, and offered to reimburse him.) I took that incident as a message from on high, to the effect that I haven't got what it takes to be an effective cheapskate.