The NFL cannot be scripted as explained by a writer for The Tartan. People sometimes struggle to accept hard truths - like if they're favorite team constantly loses. It's stated that this is a "facet of humanity in the modern age: people are driven by a desire for neat answers, even when there are none". There is absolutely zero evidence to prove that the NFL has a scripted outcome, but many people just need something else to believe just so they do not have to accept an ugly truth.
Additionally, some people blame that the referees are in on this "script", but it is shut down by Ed Collins: "Referees make mistakes. And yes, some of these mistakes are going to come late in the game, when the outcome might still be in doubt". There is no evidence or reason to suspect that these games are scripted, and all humans are surely to mess up at times, which only further refutes the claim.
Finally, according to LifeHacker, it's important to realize that "NFL teams are owned by different millionaires and billionaires, who likely wield as much power as the league. They would not accept a rigged game". It explains how it is human nature to hold such strong opinions for the teams people love, and many people want an excuse for when events do not end in their favor.
Overall, this claim is false; the NFL is definitely not scripted.