The speculations about the apocalypse usually stem from an at least somewhat self-centered personality. There's a certain... arrogance if you will, that somehow you can either predict the end of the world, or that somehow it's something special for the apocalypse to happen to you when you're alive.
That being said, it can be argued that speculations about the apocalypse is merely planning for the future. You don't know if the next winter is going to be a particularly brutal one, or if a hurricane will hit you, but you keep yourself at least somewhat prepared for if it does. Likewise, you don't know for certain if there's going to be an apocalypse, but if it does, having talked about it does give a certain level of preparedness outside of no speculation at all.
I will admit I enjoy talking about death of humanity scenarios for the philosophical aspect of it (human morality and such in light of a destroyed civilization), but the physical aspects are something I'll touch on briefly. Because quite honestly, while I do have a general zombie plan, the odds that it will work and I will survive are slim to none. There's a reason it's an apocalypse, and that's because the vast majority of everybody is going to die.