Why has the bitcoin value. "Because I can dump it on the next guy" does not address the question. That sounds like a pyramid. Nobody actually wants bitcoin. They all just want to dump it on the next guy.
Even if it IS a pyramid, this doesn't change a thing. At the moment of the exchange he who buys bitcoin values it higher than what he gives in exchange for it, otherwise the exchange simply wouldn't happen. You just can't get away from this fact, whether you like it or not. It is
subjective value that matters here. Why it is valued I have already explained earlier...