In uncertain times, there is big demand for storing value. Whereas tulips are a horrid store of value (they rot, anyone can grow them, are not divisible, etc), bitcoins are an excellent store of value. It is divisible, transferrable and easy to hide. Very similar properties have made gold a huge success as an investment vehicle. There are other goods similar to gold. For example, there are 20 billion CHF worth of 1000-CHF bills in circulation, most of them outside Switzerland. They are not used for purchases - they are used to preserve wealth. If bitcoin becomes one of those assets used to preserve wealth, its price can easily jump to 1'000 EUR per coin, giving it a similar capitalization as Swiss 1000 CHF bills.