It's a bit more than a metaphor :) during the California gold rush there was this guy named Sam Brannan who sold shovels and other tools to miners, and made a fortune from it (he is often referred to as California's first millionaire). He also had a newspaper at the time, the California Star, which as you can imagine was used to promote the gold rush:

> The excitement and enthusiasm of Gold Washing still continues—increases. (1848)

https://sfmuseum.org/hist6/star.html

https://en.wikipedia.org/wiki/Samuel_Brannan