Not to divert this thread, but if you include the number of hours people are in a car, and use the number of hours people are hiking, and then compare the death rates, I don't think the automobile death rate is orders of magnitude greater. I am sure it is higher than death by hiking, but deaths per hour of hiking, when you bring in the incidence of death by heart attacks, HAPE/HACE, hypothermia, etc, it does get up there.
Death by bear is at or near zero, but not death by hiking.
Any discussion of risk has to have a framework. I deal with low probability events (dam failure) with extreme consequence and we use annualized loss of life framework, a similar risk management approach as insurance providers, nuclear plants, and airplane safety. In each of these instances, the population at risk is doing little to contribute to their risk except living near a hazard or boarding a plane. It's a passive risk that society is generally willing to accept for the rewards that we receive. Some will move far away from a nuclear plant or dam and some will never get on a plane, but those are exceptions. As long as the risk is low enough, and the rewards are high enough, society reluctantly accepts it.
In the case of hiking or mountain climbing or sky diving or smoking cigarettes, the person is accepting unusual risk and hopefully managing it wisely. Everyone has their own risk tolerance for these activities. For some people the whole point of the activity is to push risk to the limit. Other people won't go near a roller coaster.
The other complication that you point out is the time factor. A sky dive is over in a few minutes, hiking or mountain climbing might be a few days at a time. These are hard to break down into an annualized loss of life. Driving is something most everyone does almost every day so that works well for a baseline. Furthermore, there are shades of risk within these activities - it's more risky to climb half dome in a thunderstorm than to hike a Sequoia grove in sunny weather.
If this isn't enough complication, how do you measure the risk? Should you compare it to the entire population or just to the people who choose to do that activity? This is where getting hit by lightening seems impossible to the average person, but quite likely if you work in a fire lookout on a mountain top. The risk is then portrayed as "1 in a million chance" of getting hit by lightening.
One last point about risk is the perception factor. Society is less accepting of risk to a large group of people all at once. There are about 30,000 auto deaths each year, almost 100 each day in the US. It barely makes the news. But if a plane with 100 people crashes it's obviously a very big deal. If one crashed every day people would not fly. But we accept the same consequence as long as it's a few here and a few there. The other perception factor is the media. There have been what, about 70 deaths from bear attacks in the last 100 years, but people are irrationally fearful because the media sensationalizes it. People visualize the gruesome nature of it and they lose sight of the true risk.
Human nature, go figure.
