I gather that at the time, liquor made an effective currency.
In very rural farms, if farmers had surplus crop or the distance to market was far, or the price of the crop was low, conversion of the crop to liquor made great sense.
It was highly valued, easy to transport, and was very fungible for sale or trade. It also had the added benefit of being much more trustworthy to consume than drinking water.
So a wealthy man like Washington spent a lot of time brewing and distilling as liquid assets. To make such an elaborate eggnog let all his guests know that he was wealthy.
Typical Colonial liquor was ubiquitous, and had names like Rattle-Skull, Stonewall, Bogus, Blackstrap, Bombo, Mimbo, Whistle Belly, Syllabub, Sling, Toddy, and Flip. Added to these were the still popular Hard Cider, wines, beers, rums and whiskeys.
Thomas Jefferson imported lots of French wines, John Hancock was accused of smuggling wine, Patrick Henry worked as a bartender, and there is still a popular Samuel Adams beer.
Thanks for the history! Eggnog (homemade) is a personal favorite of mine ... love the stuff and I like it generously spiked. ‘Syllabub’ .... always loved that name and like it as a recipe as well.