Sad Emo explained it very well imo.
In this eschatological scenario the "end" can strike anytime, preferrably when people least expect it, when they think they are at peace and secure. Iow, it is not announced by any remarkable event -- and the WT interpretation, making "peace and security" a solemn and unique declaration, runs contrary to the thrust of the text).
Another similar perspective is found in Luke 17:
Just as it was in the days of Noah, so too it will be in the days of the Son of Man. They were eating and drinking, and marrying and being given in marriage, until the day Noah entered the ark, and the flood came and destroyed all of them. Likewise, just as it was in the days of Lot: they were eating and drinking, buying and selling, planting and building, but on the day that Lot left Sodom, it rained fire and sulfur from heaven and destroyed all of them --it will be like that on the day that the Son of Man is revealed.
A different outlook is found in the Synoptic apocalypses which do describe a chain of events (including Jerusalem's destruction) immediately preceding the coming of the Son of Man. Yet there is a trace of the idea that no particular event is the signal of the end: "the end is not yet." (Matthew 24:6) And the "thief in the night" motif again.
One consequence of the view expressed in 1 Thessalonians (the end may come anytime) is that anytime, too, enthusiasts can claim it is now. Whence the correction in 2 Thessalonians 2 that something remarkable must happen before (and is not fully here yet).
Bottom line: it is impossible to gather a coherent scenario from the NT eschatological texts (not to mention the anti-eschatological ones, e.g. John).