Ask them if they've ever run into any kind of problem, even if it turned out okay. Ask what decisions they made turned it into a non-problem. Then extrapolate the incident by adding one or two conditions that would be likely to foul up the situation: bad weather, darkness, injury, etc, and force them to think about what they would have done then.

Then use Hikermor's suggestion: "...point out where better preparations, filing a trip plan, checking the weather report, etc., would have resulted in a better outcome."

Emphasize a few incidents where people depended entirely on luck... and point out that some of those people have still never been found... even their bodies.

Sue