While I appreciate your concern for your friend, I have to agree with the others who've counselled letting it lie.
IMHO, there're so many levels of wishfull thinking and denial going on in that head of his that I'm afraid that only experiencing and, hopefully, surviving a Darwinian Moment is going to change his attitude. I'm afraid that no amount of reasoned rhetorical argument is likely to do it, as it's my impression that he seems to believe that since he already has the requisite Talismans (firearms) they will somehow magically empower him to rise to the challenge in the Gravest Extreme.
As long as he believes that any potential threat is too nebulous to warrant serious concern and preparation, there's unfortunately not much of substance you can do about it.