"Markets" properly understood are voluntary trading environments. Bitcoin was built voluntarily by individuals pursuing their own interests and using their own resources and property (some of those interests being profit, or eduction, or ideology, or experimentation, etc.). The fact that the creator didn't "sell" the idea is irrelevant.

Bitcoin would NOT have been an example of free market innovation if it had been produced via taxation and coercion (ie - by a government diktat or program).  Big difference.