Facebook was selling ads almost immediately in reality. The movie made a big deal about Zuckerberg wanting to avoid running ads on FB, but from launch, FB had a nifty native ad system in place and even gave equity in the company to an ad agency in return for guaranteed spend over time.
In fact, Facebook would not move on to a new campus unless they have made enough money to buy the new servers that they would need to move there. The worst thing that movie did was misrepresented how scrappy early Facebook was.
And, frugality is good in the beginning but after you prove yourself, you have to step on the gas.