Bitcoin is valuable (or has value, if such form suits you better) to those people who find the properties inherent to it useful for the achievement of their aims. These are security, deflationary nature, fixed supply and limited number of coins ultimately possible to mine. Probably, there are some other properties that contribute to its subjective valuation by people, but these will suffice. Once you get the hang how things actually work with respect to valuation, everything will become clear and easily comprehensible...