Peter is comparing the passing away of the 1st world through flood and is saying the current world is also reserved for fire. Not sure if the fire would be physical but the main thing is that the flood was global (not in Jerusalem only) and so the fire reserved for the ungodly today, whether physical or not, shall be global (means every ungodly men will be affected), not just the ungodly in Jerusalem.
You are making a logical error when you assume that since the flood was global that 2 Peter 3:10-13 is global. There is nothing that necessitates that conclusion other than it sounds logical to the human mind that doesn't understand the nature of apocalyptic verses. It is not global. 2 peter refers to Jerusalem's destruction and the temple in 70 AD. Josephus records that the city was burned to the ground, along with the temple, so thoroughly that it looked like no one had ever lived there.
The "elements" mentioned in 2 Peter 3:10&12 is the Greek word "Stoichea". It's used 7 times in the NT (Gal 4:3&9, Col 2:8&20, 2 Peter 3:10&12 and Heb 5:12). Do a word study on it. It is not the periodic table of elements. It is referring to the Mosaic Law. Peter is using apocalyptic language in 2 Peter 3:10-13 to describe the end of the Law and old covenant Israel. That's why Peter also mentions the scoffers of the last days in that chapter which is a reference to the unbelieving Jews mocking the Christians that He would actually come back. But God was patient not wanting any of the Jews to perish in the city (2 Peter 3:9). But that patience was to wear out soon (2 peter 3:10).
But you are mainly wrong about the 70AD events because it is the ungodly men (Romans) that dished the punishment to Godly men in Jerusalem. The disciples of Jesus were also affected.
You have this completely backwards. Read Matt 22:1-14. Jesus says in Matt 22:7 that the Romans are His armies. And He calls the Jews inside the city of Jerusalem in 70 AD wicked men. He says it many times in the gospels too. An evil and adulterous generation. A Harlot. Mystery Babylon. Jerusalem. Those Jews were Satan's armies just like God said to the Pharisees that the devil was their father. And when Jesus destroyed them with His armies (the Romans) in Matt 22:7 then the next verse (Matt 22:8) tells us the marriage supper of the Lamb (Rev 19) is ready in at the time of their destruction. Luke 19:11-27, the parable of the minas, also confirms the Jews in Jerusalem in 70 AD were wicked men.