There have always been large numbers of people who thought the end was near. I suspect they have a problem accepting the fact that the world will go on after they die.
There's also an egotistical desire to believe there is something absolutely unique about the time one lives in, I think.
Historically, apocalyptic hysteria flares up in the aftermath of political setbacks for Christians. It is not a good or healthy thing. It's pretty morbid when a love for Jesus, and longing to see Him again, translates into a desire to see bad things happen to our neighbors. Our fellow human beings become expendable stage furniture.