He just uses the word myth to mean "social construct," (which he explains in the book). Social constructs are those things we all pretend are real, but aren't o

He just uses the word myth to mean "social construct," (which he explains in the book). Social constructs are those things we all pretend are real, but aren't objectively real in the scientific sense (e.g. a country). He probably chose to use "myth" instead of "social construct" because it sounds less pretentious.