By the way, if you were to suffer a really serious injury, one

that left you paralyzed for example, I doubt that you would think it
was worth

it. Price to be paid - indeed!

*

Well, clearly, you DON'T understand risk either or you would not
have written this.

It is EXTREMELY UNLIKELY that such a fate will befall me ... but
not impossible.* If you live your life based on worrying about extremely
unlikely events then you will end up doing a Howard Hughes and never leaving
your house.

It is not as unlikely as you think it is. Helmets will not
protect you from a paralyzing injury. Bikers who ride their bikes on hiking
trails will hit something and go over the handlebars. It is not rare for this to
happen. How you land will determine how serious your injuries will be. Why risk
any of this?

Well, actually, I know precisely ... as a percentage per mile travelled ... how likely/unlikely it is. I have decided that this risk level is acceptable. I don't castigate anyone who takes a more cautious view but my choice is my choice and I, and any other adult who is mentally competent, am entitled to make up my own mind.

Of course, the reality is that the risk is variable and depends on many factors including the type of riding that one undertakes. Thus, taking one's children on the trail one would ensure that they were undertaking less risky activities whereas I would tend to gravitate towards the more extreme end of the spectrum with concomitantly greater risk.

However, since the odds of killing or disabling yourself whilst
walking down the stairs or taking a shower are also unlikely, but not zero, even
there you are not safe.

Hikers walking a trail are not in much danger of killing or
injuring themselves whereas bikers who do what they do on trails are. Very odd
that you would argue anything to the contrary.

I simply pointed out that the odds are not as extreme as you might expect. And, for this reason, a goodly number of hikers do succumb to fatal injuries as a result of hiking.

Mountain biking, measured against other risks, is not at the top
of the risk tree ... but it's not at the bottom either.* Pay your money and
take your choice.* As I also enjoy extreme skiing and motorcycle racing I
take it you can guess where I draw the line.

You are risking life and limb doing dangerous things. When the
inevitable happens you will have nothing but second thoughts about the risk
taking. It is entirely possible to enjoy what the outdoors has to offer without
doing anything foolish. I enjoy trekking, but I would never for a moment
consider any kind of climbing. Why? It is dangerous and doesn't add to my
enjoyment of trekking. Adrenalin rushes are strictly for idiots.

Risk is endemic to living. Pretty much everything that you do has an element of risk. You may eschew 'dangerous' sports but then expire from congestive heart failure or as a result of a motoring accident. I think you're missing the fundamental point ... I AM fully aware of the risks and I CHOOSE to accept them. I am not alone in that and, in fact, many major breakthroughs in a lot of fields have resulted from people prepared to take calculated risks. Given that nearly every risk is well below 100% no, nothing is 'inevitable' as you posit. In fact, most people will enjoy their activity with nothing worse than a few bruises ... that's the norm.