Lacklustre trailers, title.
With the awareness that Prometheus was crap, a sense of "Oh you won't fool me this time, Ridley Scott!" was in the air,
which most likely contributed to it's decrease in commercial success despite IMO, being a superior film in the narrative.
And a concept that we'd seen before.
(From the trailers perspective.)
It's more easy to see why audiences didn't have a interest when you compare it to what Prometheus did have.
Prometheus' the return of Ridley Scott to Sci-Fi, a cast of hot new stars and an return to sense of legitimacy in that Prometheus was described as it's own thing in the Alien Universe, the complete opposite of the abortion of AVP/AVPR people had suffered five years prior- that had little to do with the series history creatively, aesthetically, narratively or thematically beyond the creature itself.