We are not the only ones who have our apocalyptic prophesies. The Romans had them as well.
Cynthia Finlayson, Brigham Young University, USA, Inter-disciplinary.Net First Global Conference
Lactantius, quoting from the works of the Classical historian Varro, claimed that the Apocalyptic prophesies of the Sibyls (The Sibylline Oracles) were kept secret by the Romans and could only be read by specialists called the quindecimviri. Presumably this was to forestall public panic, and/or self-fulfilling actions that would contribute to the eventual cataclysmic fall of Rome foretold within numerous chapters of the Sibylline texts. It is obvious, however, that certain Sibylline apocalyptic prophesies were available and known by many beyond the elite quindecimviri of Rome. Contrary to inciting panic, the Sibylline Oracles were utilized by a number of famous individuals in Roman history as venues to power...Such a study assists us in earmarking the characteristics of ‘Apocalyptic Opportunists not only in the Classical Age, but also in modern times.
The text are here (for a detailed discussion). Fairly common with 'ancient' oracles, the Sibylline Oracles were current writings, claiming to be of great antiquity. The ancients were not particularly good at ferreting out anachronisms and textual flaws, likely attributing them to transcript copying flaws, so if you wanted to make a prophecy about current events, a popular method was to backdate your text and claim to be of much greater antiquity than you actually are. Note that this has been sited as a problem with both books that were excluded from the bible, as well as some (the Lesser Epistles of Paul being prime examples) and that were included.
So why all these pseudo- and real prophets proclaiming doom? Because there are always people that see an advantage in overturning the current order. That they may occasionally be correct is beside the point.