I think the people who believe Bitcoin gave value to it. Just like art pieces, it will be valuable according how much people believe in it.
People believe and used bitcoins only because it has got some unique advantages. For instance, let us compare the fees in case of bitcoin and PayPal. Bitcoins have less transaction fees as compared to other payment systems like card payments and PayPal. This is another reason behind the increasing acceptance and popularity of Bitcoins.
I heard that PayPal is going to increase its fees even more which will push the prices of bitcoins even higher.