It has value because of the things that you can do with your bitcoins. You're using it simply because you need it to have better transaction with other people. Bitcoin is utilitarian (definition: designed to be useful or practical rather than attractive). Without its uses, bitcoin will simply be a combination of 1s and 0s.
Personally, I wouldn't be surprised if something that lives off the internet has so much value. Just look at the CS:Go items (See: article). The items that exists on the CS:Go have a higher price than when you are going to buy the real item (for example, a knife with some engraved stuffs on it). You can also trade CS:Go items just like in bitcoins especially the ones that are seasonal/limited.