The movie shows that as well. If you don’t see that, then you are a surface level thinker.
Yeah, the movie went to lengths to make that obvious.
* All of Paul's visions of the future where he rules show tremendous death. No ambiguity.
* All of Paul's arguments as to why he shouldn't rule and initially rejects the Messiah role sound reasonable.
* They make it clear that the BG have been conniving and manipulative and that the worship of Paul is a fake religion they created.
* Lady Jessica looks evil as hell whenever she uses religious manipulation on people.
* The religious believers look like fools.
* Paul reiterates multiple times that he's fighting for revenge more than he's fighting for noble causes.
* They straight up say, "Well if we're Harkonnens, then let's be like Harkonnens", which shows they know their choices are no different than what evil Harkonnens would do.
* Like
@CHICAGO said, Paul's turn to the dark side is accompanied by almost horror movie music.
* Chani is placed as a sympathetic character who strongly disagrees with Paul's choices and is betrayed due to his decision for power.
I'd argue the book is way more ambiguous on those points than the movie is. The only reason that book readers agree that the book is subverting the Messiah narrative is because Frank Herbert straight up said so publicly.