Meet The Impossible Man
One of the least enjoyable things about daily life in the Foobiverse is the realization that Elly has very little idea that she is well off. I remember John having to pretend that losing her poorly paying sinecure at the library meant that they had to cancel buying new furniture because he knows that she thinks that her paltry contribution to the finances is vital.
This is the reason that is not John being a cheap son of a gun that prevents him from getting himself a business manager to take care of the finances. It's all he can do to not break down laughing when she says that Liz has too many expensive things that she didn't earn so pointing some drone at her and trying to get the twit to understand that yes, two people can have three cars is a waste of money.