while TS want it to happen so he can go "I told you so."

Well that's the difference I think between being a doomer and having a realistic, if pessimistic belief. There are plenty of reasons to think we can not dig ourselves out of the hole we are in or that it's a battle too uphill for people to commit to.

Like all things, there are levels when it goes from understandable (even if we disagree) to useless circlejerking just to fluff your own ego. Doomerism is the people who were certain we'd have boots on the ground in the Middle East that weekend, and will scream at you for bringing up any possibility to the contrary, and have not mentioned the topic since because it was meaningless beyond their own ego, as you pointed out.