What makes people still watch Hollywood movies even though everyone knows what’s gonna happen?

There is a philosophy that there are only seven different stories to tell, in terms of core ideas.

Predictability doesn’t mean something is bad. Good writing, directing, character development, can get someone invested in a predictable story.

Once you know the twist of a movie that has a twist, the suspense is gone. You can never see that film the same way again. In that instance, unpredictability becomes a hindrance. Likely, if a twist is spoiled for you, you may have less incentive to see the film at all.