Bitcoin is FIRST BEST:

"Second best refers to the solution of a decision maker's optimization problem when the feasible choices are constrained by an economic friction that does not allow the first best to be reached." May 1, 2018

https://link.springer.com/referenceworkentry/10.1057/978-1-137-00772-8_445#:~:text=Second%20best%20refers%20to%20the,first%20best%20to%20be%20reached.