It's a mix of cryptography, freedom of speech, computing, networking, finance, economics, and even politics -- most of us here dig that stuff.
Yes, but we usually recognize things as belonging to one or more of these categories. For better or worse, trying to explain to the vast majority of the population what a Bitcoin is has been akin to saying "Play Minecraft for fun and profit!"
I don't think it's any more ludicrous for Bitcoin to have value than it is for gold to have value.
That's quite possibly fair. But if you buy into the theory that all of the gold on Earth was likely created during numerous supernova billions of years ago, you just might have a hard time comparing that to a Bitcoin.