Okay, I'll put things very simply and bluntly:

From a point in the history of any civilization, you can't predict with any accuracy how long that civilization will last. Period. For all we know, we could all be wiped out by a NEO in a few decades... Or we could be at the beginning of a civilization that survives billions of years into the future, and colonizes the whole galaxy. We don't know, and furthermore cannot find out until something actually happens. So y'all quit yer catastrophizing and do something useful, and we might actually have a chance of surviving whatever comes up!