the question is, why would a hoarder get 'scared'? at this point the hoarders are mostly people who mined EARLY -- ie: their investment isn't substantial in most cases.
I wouldn't say 'scared' is the right word - but what the poster you quoted meant was that there's ~3000 BTC worth of BIDs on MtGox at the moment, after which the price of a single bitcoin is... well, zero, unless someone makes more BIDs. If the hoarders (aka. early adopters) have 1k+ BTC (perhaps even 10k+ BTC?), it's basically a game of chicken: the one that sells first gets a profit in USD, and after he/she has dumped all of the BTC, the price will plummet, and the other hoarders BTC will be worthless (vs. USD, of course, if you like alpaca socks, they won't be
. All of the people with a lot of BTC know this, and the counterbalance against selling right now is the possible increase in BTC/USD exchange rate - "why would you sell now, when it could be 12 USD/BTC soon?".As long as there's no 'real' value to BTC (aka no major merchants accept it, and only a very few selected small businesses do), this is what it boils down to - which one of the hoarders dumps their BTC first
The community, of course, can counter this by creating a real value for BTC: by getting businesses to adopt BTC. However, it may be hard, since as the investment goes up, people do background research, and sooner or later they will bump into the fact that most of the BTC is in the wallets of the early adopters (which is why the poster you quoted referred bitcoin to a pyramid scheme), which makes the economy unstable.
Just my .02 BTC...