Not exactly what you are looking for but a related quote by Charles Bukowski: "The problem with the world is that the intelligent people are full of doubts, while the stupid ones are full of confidence".
Often, on HN and Reddit, the most confident or authoritative sounding statements are also the most wrong. It always baffles me just how confident people can be in themselves when they really have no good basis for that confidence.
I think part of the problem is that we collectively tend to reward the "confident sounding" comments because we wrongly assume that only an actually knowledgeable person would have authored them.
Isn't it a paraphrase of Bertrand Russell?
"The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt" — from The Triumph of Stupidity, 1933.
1. Absolutely no one expected an actual war with Ukraine. When the first news in english press were published (in November I think) about the coming war between Russia and Ukraine, everyone I know just simply dissmised the very idea of it. It seemed absurd, unthinkable. I did not believe there was any possibility of the war whatsoever and so were my friends, my colleagues, my parents, the ukranians I know. The news became a common joke, a meme even. So when I woke up Feb. 24th and opened the internet, I was stunned, appaled and absolutely embarrased on top of it. I've never read or heard that it is possible to feel enormous embarrassment about the delcaration of war, but it was the strongest feeling in me at the time (and reading various russian sites - not just in me). Despite various disagreements between the Russian and Ukrainian governments, the news about war seemed bizarre. It would be similiar to waking up one day and reading that US Navy are blockading Liverpool and Bristol, US Airforce are bombing London and Manchester, and US Marines are storming Brighton and Southampton. Absolutely surreal. It took a full week for this feeling to slowly fade away before I regained my ability to think straight; I just couldn't work or do anything productive during that time, I was glued to the news and even more news. My father still haven't recovered - he lost all appetite, doesn't talk with anyone and overall extremely depressed.
2. Reading various russian sites - the first reaction was very negative and almost no one supported the war as it happened. After the first 3-4 days the opinions started to change. People started to mentally cope with the news and invent various rationalizations in favour of war - nobody like to be a "baddie" or feel like one. So the opinion is slowly swaying towards the side that claims that the war is justified. That said, I believe even the official russian TV-propaganda were shocked and didn't know what to do or say at first - it took them several days to find the right groove. Propaganda-wise, there was zere preparation of the population for the coming war. The main downside of constantly manupulating statistics is that it is impossible to know which numbers are genuine and which aren't. It could really be that 70% of russians are supporting the war. Or it could be 50%. Or 30%. Or 99%. There is no way to know for sure.
3. On top of that no one really knows or understands what is it exactly that our army are fighting for, what are our end-goals and, especially, what exactly will happen if Ukrainian government will refuse to sign a peace treaty and deside to fight till the end. "Demilitarization" and "denazification' are extremely abstract goals with no clear purpose. There was (and still is) a strong emphasis that the russian army will not target civilian buildings and infrastructure (and soldiers are genuinly reluctant to do so). But it is plain to see now, that this goal is impossible to achieve in the modern war. So what do we do? Do we start to level Kiev and other cities to the ground? Do we march on Lviv? Just what is the plan? Nobody knows.
4. As for the future - right now I am genuinely more worried about the Ukranians than about Russia. I have friends in Sumy who are now almost two weeks under siege, and who knows how long it will last. The Ukraine itself is suffering an enourmous damage to it's infrastructure - how and when and with what funds it will be restored I have no idea. On top of that it looks like there will be at least 5.000.000 refugees (and probably much much more) - their fate is also unclear, I don't think EU can adequately deal with such a large number. In comparision the devaluation of the ruble doesn't seem as important. It looks like there are three main fears: 1) a large scale unemployment - a lot of businesses are leaving Russia, producing an enormous chain reaction; 2) lack of essential medicine - a lot of drugs are imported from the EU (Germany in particular); 3) complete default of the state - a lot of people have lived through the 90s (which in Russia were somewhat equivalent to the Great Depression in USA), so a certain level of impoverishment and hardship are ok, we are used to it, but a complete bancrupcy will be catastrophic. I don't believe there is any chance for an actual famine. The rest isn't so important in comparison.
5. It is also important to understand, that even in an unjust war it is impossible not to support and sympathize with your army. Wishing death and defeat to your own soldiers just isn't right and would feel dirty.