Simple, because it's new, and it kinda makes you rich much easier and quicker. Everyone wants to adopt it in an early basis.
And it is also because people became curious about it and they really want to try if they can really earn a profit if they will try to invest in it. To those people who are already rich it is very easy for them to buy bitcoin even if the price is quite big. Unlike us who only have small money, we will always wait for the time that its price will become affordable. So that's the reason why there is such a demand for bitcoin.