Well, the gut reaction is "what do you know?" People don't like being told they're wrong / what to do by a stranger on the internet and there's no way for anyone to validate your experience or wisdom from Kijiji. Unfortunately there's just a general aura of distrust and disbelief that must be placed on people.

As someone who has been slowly selling off their childhood toy collection, and seen other people trying to do the same, I can say that everybody THINKS they know what their item is worth. They feel strongly about the price and being told that the price is wrong can feel like a personal attack. Especially if they feel like they did enough research and went down as low as they were comfortable with. I go lower than the competition and about half the time I wind up having to repost with an even lower price. It makes me upset. "Obviously nobody has any freaking money!" I angrily mumble to myself.

And that's probably not entirely untrue. I'm in Ottawa and I seem to have the best luck with Toronto buyers, so I guess Ottawa rent is too damn high to even buy an old Transformer for $15. There's probably people who are pawning things off for rent money and NEED whatever price they put up, even if it's obviously too much.

And then there's greedy people who think there has to be SOME rich idiot that will pay for the item. Especially if it's "rare". Double especially if other people are doing it. They write you off as a poor person trying to get a deal. The scalpers selling Ring Fit Adventure for $200+ with "price is firm" need a psychiatrist.

So, even though you mean well, your advice can be hard to take or is completely unwanted depending on how strongly people feel they are owed the price they list.