It's impossible for one guy to know everything. I'm a programmer, in that field alone it's impossible to know everything. You chose your niche and try be an expert in that. If you do know something else as well, good for you, but it's very hard.

Suppose a large portion of humanity would die out. One scenario would be a global killer meteorite*. Ofcourse, if you are in the kill-zone it doesn't matter if you're smart or dumb, you'll die (if not evaporize).

But if you survive the onslaught, you need to FIGHT!|

If you fill your days buying that new mobile phone stacked with gadgets every 3 months while stuffing junk food in your mouth, doing no sport activity (or exercise) at all, or any high activity vacations, your chances are virtually zero.

Suppose you'd get a helicopter and grab random people from the major cities of western society and drop them in the middle of the wild, the vast majority would give up immediately. The rest would fight. Still, many people might surprise you, and prove to be more resilient than you'd guess. It's like the matrix, once you're in your cushion life too long, it's too late to be pulled out.

I like (close to) zero-comfort vacations**. Ofcourse, I like to return to my high luxury life, but I know that if it weren't there anymore I'd adapt and fight. I wouldn't like it, but I'd work on making life as comfortable as your environment allows. I know many people who's chances I'd estimate very close to zero.

People who's life is ruined once their nails can't be manicured on a daily basis anymore, would soon be extinct ofcourse (and good riddance ).

A good physical condition is an advantage, but before anything else you need mental strenght. You need to be a fighter. That doesn't mean you should be egocentrical, cause they don't last in the long run. You need to be strong in the face of high discomfort and still be able to laugh.

Many people I see do not qualify for that. In the least ...

* Which I also mentioned in my post in reply to Odrirg
** The kind that makes you think of a board with a hole in it, as a toilet, as a luxury.

"What is mind, don't matter. What is matter, nevermind!" - Homer J. Simpson.