Earlier quoted context omitted.
You fail to realize that Overstock represents a tiny fraction of all the commerce done in bitcoins. Bitpay alone is seeing an exponential growth of Bitcoin transactions: they appear to be doing about $20-30 million/month at their current rate: http://blog.bitpay.com/2013/12/bitpay-drives-explosive-growt... and http://blog.bitpay.com/2013/12/bitpay-exceeds-100000000-in-b...
That's still astronomically low compared to non-bullshit money. The US economy goes through its M1 money supply 7 times per quarter, or over twice per month [0]. If Bitcoin had that ratio, it would now be running $30 billion of meaningful transactions per month, not $30 million. [0] http://research.stlouisfed.org/fred2/series/M1V [Ctrl-F keyword: "velocity of money"]
In reality, there are many more payment processors other than Bitpay, and many economic transactions happen outside of payment processor networks. It is hard to estimate money velocity in Bitcoin: http://blockchain.info/charts/estimated-transaction-volume-u... shows approximately $3 billion/month ($100 million/day) but this is an upper bound, because some of these transactions are just people moving coins around their wallets. The real figure is probably $100+ million/month to give an order of magnitude. And $100 million/month is not bad at all considering that it started from zero merely five years ago!