IMO it's because the stock photo of "the 1%" is a superyacht or a private jet, which makes people like HNers think that they themselves are far below the threshold.
A private jet in the case of this article. I bet that's not how HNers would illustrate us as a group. Quite a nasty rhetorical trick, really.
It depends on whether you're talking about the top 1% of the US, or the top 1% of the world. The latter is a much lower bar.