It seems pretty backwards compared to any other sort of creation. If I build a house, my basis is how much I spent building it, not how much my neighbor's house is worth.
I don't think this has anything to do with basis. The difference is that mining the coin is considered a tax event -- so you pay tax on the mined value -- with the cost being deductible. This makes sense because the coin is liquid and can be sold in part without reducing the utility of the remainder.
That is not true of a house. It isn't as liquid and it's hard to sell part of the house to cover tax.
