10. Helping The Wounded Man - The Purge
The first Purge movie is largely confined to the home of James Sandin (Ethan Hawke) and his family, and had they all just stuck to his incredibly simple survival plan, everything would've been fine.
James assures his family that their home's high-tech security system will keep them safe from Purgers, only for his son Charlie (Max Burkholder) to notice a wounded man (Edwin Hodge) outside and, after barely a moment's thought, he disables the security system to provide him sanctuary.
Was Charlie's act the morally "right" thing to do? Probably, but it also ensured that the Purgers hunting the wounded man turned their attentions to Charlie and his family.
To make matters worse, Charlie even helps the wounded man hide in the house while the rest of his family attempts to locate him.
Though Charlie survives the night, his "selfless" behaviour ultimately results in the death of his father. It's really only a minor miracle that he didn't also get himself or the rest of his family killed, though, and all he had to do for a peaceful night was literally sit tight for 12 hours.