It's hard to tell, because we don't know who hides under these attacks. I don't believe this attack was made by North Korea. I don't think that their hackers is such powerful to make attack which affected people in over 100 countries.
My personal conspiracy theory: maybe attack was made by group of people who are working in big IT corporation and they found security breach and found way how to benefit from it. So, I think these who made this attack is only winners in this situation.
Not necessarily "people who are working in big IT corporation", but clearly not some little hacker trying to get bitcoin.
The mechanism that caused the malware to spread outside the networks it was in is not known by a lot of people yet.
Most likely it involves a flaw built into Windows and meant exclusively for the use of government agencies. There is additional public information that points to this, though it is not discussed much. The hacker was most likely an employee of some government who was aware of how to trigger these hidden Windows modules, though he/she could well have been from any govt as the existence of this is somewhat known and is described in a roundabout way on public sites.
Then a person should ask "What was the goal of making such a false front attack"?
Today we see a much bigger attack based on the same malware, used to "mine Monero". The timing, and the fact that the new malware is less hostile to the public, suggests a possible motive.