My personal philosphy has always been a similar state of expecting nothing, because you'll always be either correct or pleasantly surprised. But my issue with doomers is that they always seem to take everything to absolute extremes. They aren't just pessimistic, they're adamant that we're going to be living in a dystopian novel or apocalypse movie very soon, just you wait and see!
And they'll never admit they're wrong, either. I can't tell you how many predicted horrible disasters and ends of the world I've lived through, and every single time it ends up being a mediocre nothinburger. It's not good, certainly, but it's nothing that means everyday life won't go on for most. But the closest doomers ever get to acknowledging this is "well, that doesn't mean something that bad won't happen next time". They're like an anxiety disorder personified. I think on some level, they want the world to actually fall apart because it would make them right for once, and then they could rub it in everyone else's face.