I'm amazed at that a lot of the discussion around Bitcoin ignores one crucial fact - you can (relatively) safely buy illegal drugs with them. This makes it attractive to a lot of people who would like to buy drugs but don't know how to get them, or are scared of being personally involved with dealers and possibly gangs, and of going to jail.
I have never done this (nor even owned Bitcoins) but for the people I know who're talking about Bitcoins this is the main motivation for having them. Indeed, to many of them Bitcoin = Silk Road.
To counter your anecdotal evidence with my own, I know a fair few people who have bitcoins and not one of them has any interest in the fact they can be used to buy drugs.
Of the people I know It's roughly an equal split between speculation on its value and longer term interest in its potential as a low friction, decentralised currency.
Not to say it's not some peoples motivation but I think that they're probably in the minority. There was a piece which was on the front page of HN a while back (can't find the link right now) which estimated the total revenue going through silk road and it was a fairly small fraction of the total bitcoin transaction volume if I remember rightly.
FTA: "From a public relations standpoint, this is a positive sign for Bitcoin: the legal Bitcoin economy is now almost certainly larger than the illegal one, especially when one takes other merchant services like WalletBit/BIPS and Coinbase into consideration, and is growing at a much faster rate."
I have never done this (nor even owned Bitcoins) but for the people I know who're talking about Bitcoins this is the main motivation for having them. Indeed, to many of them Bitcoin = Silk Road.