Definition & Meaning of "[throw] good money after bad"

What is the origin of the idiom "throw good money after bad" and when to use it?

The idiom "throw good money after bad" is believed to have originated in gambling or betting contexts in the 19th century. This phrase is used to caution someone against making further investments or spending more money on an unsuccessful project or situation. It is often employed to advise against continuing with an endeavor that is unlikely to yield positive results.