I'm also a big believer in blockchain teachnology and like you, cant quite wrap my head around why these coins are worth so much. If found this after a little googling:

"Because things that are durable, transferable, divisible, scarce, recognizable and fungible have value. Bitcoin is all of those things, and all of it is backed by an enormous distributed network of bitcoin miners and a worldwide network of bitcoin nodes. How much value depends on how much people trust bitcoin and how widely used it is, and because that is not knowable at this point, bitcoin is very volatile in relation to other currencies."