This situation was for Iran to save face. They had to appear to "retaliate" for the bombing that killed some of their generals. They, and the powers that be, knew that none of those drones would make it through the Israeli missile defense systems, but they had to have a show of something.
Places like Iran know that they have nothing to offer, in any real military attack. They have to resort to terrorist, guerilla warfare through proxies. There is no such thing as a WW3 with Iran.
They would have to align with the rest of the middle east, China, Russia etc...for it to become another World War. None of these countries can do anything on their own.