The operative word in your post is "could".
A meteor "could" strike the Earth next week and eradicate all life.
You or I "could" get hit by a Mack truck while we're crossing the street.
While traveling at 70 mph, my car "could" have a blowout in the left front tire, thereby sending me across the median, meeting you head-on and killing us both.
"If" is said to be the biggest word in the dictionary. For tree- and bunny-huggers, I think the biggest word is "could".
Yes but do we not take resonable precautions to try and avoid those situations? Of all the things you listed, we are away of all those dangers and have taken some reasonable precautions. It's one thing to not go crazy postulating the coulds and it's another to completely ignorant of potential danger.
Why are environmentalists like watermellons. Because they are both green on the outside and red in the middle.