This has always puzzled me. A lot of people post charts and refer to trends and history to show that they're right, history shows nothing and trends change but some are blind to this, it seems. A perfect example is how everyone was always citing that the Wii was tracking above the PS2 within the same time window, some people (I was one of them) tried to maintain that the Wii is not the PS2, the differences are vast, really vast. The Wii was late to the party, did not come off of a successful predecessor, never achieved such massive marketshare, had virtually no 3rd party support and it was technically completely inferior to the others and is/was acting in a market that is not only increasing in pace but also diverging and branching out (they even aimed specifically at that very audience).
And here we are, years later, Nintendo are close to launching their new console, despite many saying that they would never ever launch first in the 8th gen. They never snagged the 3rd party support they were assured to get since they became the market leader in sales. Nintendo did kill the console prematurely, despite insistence that this would not happen since they were doing so well. They also cut the price several times, despite people claiming they didn't have to, they released all the savior software and released colored consoles, to no avail. The whole running joke and ridicule surrounding the "the Wii will suddenly just stop selling" has come eerily close to truth. 50% marketshare remained illusive and ultimately impossible. And, of course, it will never outsell the PS2 (perhaps not even the PS1). China and India weren't the savior either (they were never going to be, that much made sense).
All in all, the hardcore Nintendo fans on this site have been more consistently wrong than anyone else in vgchartz history since none of their predictions have reached fruition. And these were the people who were the most self-assured, confident and condescending on the boards all along, laughing at everyone who dared question their stats and charts and trends and history lessons (I've learned the same history but have drawn different conclusions based on it; i.e, I've been delusional and practiced wishful thinking). One can also note that the worst offenders have all but left the site and refuse to speak on the matter at all, a true gentleman can not only admit to being wrong but also discuss the grounds surrounding the whole issue. This is how one evolves as a debater.
On a personal note, here are some things that I have said and predicted over the past five years;
"The Wii is a sprinter, not a marathon runner." "Historical sales curve might indicate a historical decline." "The Wii will never reach 50% marketshare." "The Wii audience is more fickle than those of the HD twins." "The Wii will never outsell the PS2." "Nintendo will be the first to release their next console." "The next generation will start in 2012."
And there are more things. I've been wrong on many occassions as well but I never raised the stakes to the level of some others and I never stated anything as assured or fact, simply as my opinion based on my own view on things (or as some have called it over the years; "wishful thinking", because if you thought differently, you were delusional. Yes, that very phrase was thrown around a lot in here at times).
In closing, I would like to add something; I used to see the Wii as the enemy of modern and future gaming, I really and honestly did. I don't any more, my view on that matter has completely shifted and fallen upon the Hollywood-esque Press Win Button Watered Down Ghost of the Past gameplay fronted and carried by the HD consoles. I am not a hater, but I do advice everyone to be a bit more humble when predicting things and also when analysing and countering other peoples' predictions.
Because, X event and Y event may strike at any given moment.
I completely disagree with your logic. If someone makes an irrational prediction, that person is effectively a madman and deserves all the hell he gets, regardless of whether or not it turns out to be true.
Suppose I tell you that a normal coin will always land on heads, no matter what. I assert this statement and make the prediction that, if you flip your coin, it'll land on heads, no matter how many times you try. I don't care about your freaking logic; just try and use evidence to disprove me. At this point, a coin is flipped, over and over, landing on heads each time. Of course, this is unlikely as hell and I had no rational basis for predicting this, but nevertheless, my prediction is right. Does that make you a moron for trying to tell me that I'm delusional to think that a coin will always land on heads? I don't think so.
The same logic applies to this prediction about the Wii. Sure, it turned out to be closer to reality than most predictions at the time, but that doesn't mean that he didn't deserve hell for it. Now, if he had properly listed reasons for the Wii's failure, saying that Nintendo will release no more blockbusters like NSMBWii and that third parties will never be attracted to it, in spite of its sales, then we should be worshipping him and serving crow to all his haters. Notice the OP, though. You see any well thought out argument that turned out to accurately reflect reality? Not really. He says that PS2 sold lots and Wii will sell less, even though it's tracking ahead. Why? 'Cause it will.
Now, I'm not sure about the OP, but the rationale for just about all these Wii doom predictions pre-2011 was the same, "Nintendo is for kiddies and hardcore's where it's at! You'll see; even though Wii has completely destroyed all records so far, I'm sure Nintendo will pay and the stupid Wii fad will die!" I'm afraid that such an argument, regardless of whether or not it yields the correct result, is absolute nonsense.
I'm not necessarily saying that you had such an argument since I'll concede that you're fairly rational and calm about this, but the vast majority of predictions about Wii's doom had a fanboyish basis. I mean, the entirety of your predictions that you've listed is just assertions (unless you had the right reasoning but haven't listed it), with the Wii users are fickle part being a thinly veiled dig at Wii's audience, in all likelyhood. Since you admit to having disliked Nintendo at some point, you can't blame people for thinking that you just hated Nintendo and were venting this through pessimistic predictions and therefore giving you hell for it.
Of course, your main issue with this whole thing seems to be the fact that you think Nintendo fanboys have been more assertive and arrogant about their predictions. That, I'm afraid, is horribly subjective and is likely to be affected by the fact that you hated Nintendo, which meant that you saw more evil in the Nintendo fanbase than anywhere else. As someone with Nintendo-tinted specs, I can tell you that in all the time I've been here (and I've been lurking here for a hell of a long time, not to mention all the old threads I've looked at), Sony fans have consistently been far more arrogant than Nintendo fans. This just goes to demonstrate that this point is moot since we're both probably very biased.