The phrase "If you build it, they will come" originated from the 1989 movie Field of Dreams, starring Kevin Costner [1]. However, it is important to note that the actual quote from the movie is "If you build it, he will come," not "they" [1]. The phrase has since become a popular cultural reference and is often misquoted.

Meaning:
The phrase is often used as a metaphor to convey the idea that if you create something that people want or need, they will come to you instead of you having to seek them out [1]. It suggests that by building or creating something valuable, you can attract an audience or customers.

However, it is worth noting that the phrase is sometimes used as a business mantra that contradicts the marketing principle of establishing a need before creating something [3]. While the phrase implies that simply building something will automatically attract people, in reality, it is important to consider market demand and establish a need for a product or service before investing in it.

Learn more:

1. Where does the phrase, 'If you build it, they will come ... - Quora
2. If You Build it, They Will Come - Fact or Myth?
3. Idiom Origins - If you build it, they will come - History of If you build it, they will come