d=um=email&utm_campaign=nypdaily&utm_content=20180829&mpweb=3D7 55-7276831.719004712> NY='s richest couple buys $40M mansion on a whim By Jennifer=Gould Keil <https://nypost.com/author/jennifer-gould=keil/> <https://t=enypost.files.wordpress.com/2018/08/david-and-julia- koch.jpg?quality=90&a=p;strip=all&w