BitterTea produces, for example, tea; Ribuck produces carrots and I produce fish.
There's only 3 gold coins in the island.
If one of us has the 3 coins in some certain time and hoard them, there's no possibility of exchange between the others but by barter or issuing IOUs.
now let's imagine that there are 21 million coins and 2.1 billion of bitcoin users. What are the odds that they ALL will decide to hoard their average 0.01 BTC and will not part with it even if it suddenly worth twice as much as day before. Care to do the math?
Ok. Again, I'm not saying that hoarding could ever stop commerce, just slow it down. Because not everybody is going to hoard the money.
There's 21 million bitcoins out there.
There's a 3% annual deflation.
Nobody will start a business that doesn't give him more profit than the 3% that he is getting for just hoarding his money.
What is better for society?
Someone living from doing nothing or someone investing the money in some enterprise at a risk?