You say Bitcoin units hold nothing, like empty boxes. But aren't empty boxes valuable too? Collectors pay a fortune for limited edition shoeboxes!  Maybe Bitcoin is the ultimate limited-edition digital box.  Who knows, maybe someday people will be fighting over empty Bitcoin wallets at museums!

As for the whole "non-existent asset" thing, tell that to the folks using Bitcoin for everyday transactions or those holding it as a hedge against inflation.  Maybe it's not the Mona Lisa, but scarcity and utility do hold value. You don't have to admit it, but it's a fact.