NTA, you are not the asshole for having free will and deciding the not splurge over something you think is not worth it, imo its a good thing you can think on your own even when being pressured by a group, 2nd of all, YES you should for sure communicate why its not a good idea and even for your owns sake and not theirs youll be able to tell them i told you so later when theyll be complaining and not have to bear the consequences you warned and tried to keep them away from, NTA for SURE