I used to ‘hang’ with a billionaire friend of the family and, maybe that might be dutch, he was incredibly frugal (drove a crappy old but not classic car, lived in a rather small house etc) and yea was obsessed with making more. He would ask me out for a coffee and ask to split the bill (or just pay his part and walk wait for me to pay my part) even though I usually just paid as I don’t like going dutch. He spent almost no money during his life. Guess that is all good for making fortunes.