I rather figured Tom would act that way. I can't help but think, though, that such an attitude will lead him into trouble in the long run as he underestimates Harry yet again.
I can't blame Harry for a paranoid outlook on what Dumbles might do/try (I suspect he may could give Moody a run for "most paranoid" at the moment, though in his case "they" really -are- out to get him).
I can't blame Luna a bit and the cheerful note I referred to was her private musings, not her public utterances.
I wonder if, now that he's "lost" Harry, Dumbles will try and use Neville in the role he was originally grooming Harry for. I suspect that, after seeing what happened to Harry, Neville is going to be rather more careful himself, as well as Harry et al. watching out for their good friend. I can see where this could develop into s very interesting situation.