Speaking from the psychological point of view, when you focus on something so intensely, it can create expectations and even hopes. Some people who focus on such end time beliefs, to the exclusion of other aspects of their religion, feel the need to attempt to bring it about or begin to become separated from society as a whole. It is when that belief overwhelms all other living and belief.

Regardless of what religion it is (and I have studied most of them), there should be a balance between living life to have meaning and preparing for what you believe will come to be. Preparing is not bad, obsession is bad and can destroy any hope of living a meaningful life.

The media is full of content that exacerbates this type of anxiety, as well. Just look at Wikipedia for a list of post-apocalyptic movies, it is extensive. The media you consume can affect your mood, beliefs and expectations. Just think about someone who expends all of their time and resources on preparing for doomsday, watches all of the movies and TV shows. They begin to WANT it to happen (I have met some first hand). There is also the example of some cults that center around an end time event. Some have attempted to bring it about (Aum Shinrikyo in Japan, The Concerned Christians in Denver). If you focus on such things, it is very likely to cause anxiety.