(See also: Dialogue Tropes)
Merriam-Webster gives a definition of "trope" as a "figure of speech." In storytelling, a trope is just that — a conceptual figure of speech, a storytelling shorthand for a concept that the audience will recognize and understand instantly.
Above all, a trope is a convention. It can be a plot trick, a setup, a narrative structure, a character type, a linguistic idiom... you know it when you see it. Tropes are not inherently disruptive to a story; however, when the trope itself becomes intrusive, distracting the viewer rather than serving as shorthand, it has become a cliché.
- Television Tropes and Idioms
You Can't Make An Omelette...
Stock Phrase that means that in order to achieve something, it is inevitable and necessary that something should be destroyed or sacrificed. Villains in particular are fond of using the line, as it perfectly underscores their disregard for the lives they are destroying or ruining for the sake of their Evil Plan. - You Can't Make an Omelette