If the point is driving people to buy some bitcoins, then this is not the forum for that. And people really need to be aware of simple-minded manipulations that can be and are played with the bitcoin market.
Also how is it a scam, if the technology is open? It is exactly clear what BitCoin is and does. Everybody can take the specs and program their own client. Nobody can claim "BitCoin cures cancer" or something that.
Now if the current exchange rate is justified is another question. Also obviously people holding BitCoins are interested in making it more popular, as that is also related to the exchange rate.
I don't think that automatically makes it a scam, though. It is not so different from people invested in Google or Apple (either via stock or via technology usage) are interested in making Google and Apple more popular, as it increases the value of their investment.
Then again, perhaps the whole world is just a scam.
People are interested in it and that's why it gets upvoted. If you're not interested just don't read it.
"Google is a large technology company which runs the world's most popular search engine."
These are NOT good stories for HN, because the people here /know this already/. There is nothing wrong with introductory stories as such. In the case of bitcoin, there is also a suspicion of an ulterior motive in promoting bitcoin stories.
As for "don't read it" -- forums are damaged when the noise (and spam) level is high. I can express my opinion by commenting, unless a moderator tells me not to.
At this point, the Bitcoin story has been pretty well picked over, and I'm not convinced there's anything new to say.
And, the fact that the stories continue to get upvotes is precisely what is troubling.
So really the only way to get the stories to fall off is to stop talking about them.