I don't know masses on Amityville and never seen the movie but the claim on the book was based off a true story which has since been disputed - people searched the house and didn't find any damage to match what occurred there etc.

Just putting out that the thing behind it all could have been close to the location, hence missed, still hidden. So there's sort of something going on with it still somewhere around the area - and maybe the attention from people interested was wanted to play into it somehow. People going to see the famous house go, see, not impressed but every now and then a few people vanish oddly but it's never linked properly to anything supernatural since the location is dismissed as bogus, that those are crime/personal related disappearances. Like a real horror hiding in plain sight, overlooked for so long.