It depends on how they got their income in the first place. My family are dairy farmers and frequently trade cattle at local auctions. This is still a cash based society (rural Ireland), it does not take many heads of cattle to make up 10k, many other deals are done informally (e.g. my grandfather buying cows from a neighbor without auction) with a value that is of that order. The money may hit a bank account if something more formal needs to be bought (insurance, new machinery etc) but those are not all that common.

As a child I would always remember my grandfather carrying (at least in the house) large rolls of bills.