The war against Iran did not come out of nowhere. The USA has been overt about wanting "regime change" for Iran since 2001, and since Trump's last term especially. Meanwhile Iran has been very open about how they would respond in case they were attacked by the USA: punish all US-aligned countries in the region, close the Strait of Hormuz, close Bab al-Mandab, and target Israel directly and indirectly.
So this was very predictable and that's why lots of people have been talking about it since 2017.