The expending of resources to create bitcoin is not relevant to its value. If it was than this would be an example of the labor theory of value.
It doesn't create value, but it does prove value. Pearls aren't valuable
because people dive into the ocean to get them. But if you observe someone dive into the ocean to get pearls, that proves he does value pearls. If people spent time and computer resources in order to aquire bitcoins that means they had value. Since people did this before there were any exchange value, we have proof that bitcoin had non-exchange value before its exchange value.
Now we can speculate why bitcoins had value even without any exchange, but that is irrelevant to the regression theorem. Value is subjective.
Any none-exchange value makes the regression theorem valid.
But i really believe mises was correct when he said that all value is derived from the subjective preferences of consumers and not from the labor put into creating something.
Yes people spent real resources to create bitcoins before they were used in exchange, but thats because people were speculating on their future utility as a media of exchange, not because they had any existing utility in that capacity, or any existing utility in any capacity (other than as a speculative vehicle).
I guess you could say they had non exchange value as a speculative vehicle for future exchange value. maybe that satisfies mises criteria but at this point my brain is beginning to tie its self in knots. (im not as smart as mises)
I've had similar thoughts as you here. And while it does seem somewhat circular I don't think it breaks the regression theorem, and it's a plausible theory.
But there are other possibilities as well. People often talk about gold's "intrinsic" value, and while gold do have some industrial uses, what people tend to forget is that back when it became money, it really didn't. It was a useless yellow rock that you couldn't do anything with. Basically, its only use was esthetic. Bitcoin could easily fit into that same category. Bitcoin is very esthetic/interesting to a crypto geek, making him want to aquire some even before there were any exchange. This could be bitcoins non-monetary value. Bitcoins intrinsic value could be "geek points".