Re: [1969912] major base-risks?
Your post tells me you know a hell of a lot more about BASE and risk than many active jumpers.
You have a recurring theme in the examples you have given r.e. flying and climbing.
Operator error. Human Error. Poor Decisions. yada yada yada
I do/have done all three (BASE, flying, climbing). Psychology, knowledge, training, and experience plays a major part in safety and/or advancing to higher levels. It also plays a major part in accidents in all three disciplines.
I have been saying for a long time that jumping from an object is NOT necessarily the most dangerous aspect of this much loved activity. IT IS THE DECISIONS THAT IT"S PARTICIPANTS MAKE THAT HAVE THE GREATEST IMPACT (pardon the pun) on our statistics. This is not about luck, or about risk, or about intervention from higher beings, etc. It is 99% about the decisions we make. And the most important decisions are made BEFORE we jump. Quite often the most important decision is made even before the first BASE jump.
What I mean by this is that many people are so focused on the final outcome, the doing, that they miss all the steps in between. When the proverbial "shit hits the fan", they are unable to manage the situation. They made a decision up front to miss development steps and the opportunity to assess their progress. And their lack of knowledge has meant that they could not make the right decision when most needed. The second decision would have been potentially a lot easier if the first was correct/justified. Just accepting the perceived and going on with it IS NOT managing risk.
In reply to:
but there seems to be a lot of "i wouldn't have done that"s on the List. It cannot be that simple, though, right?
Heh, heh, heh. Harry hindsight knows it all. It usually is simple. We are humans. And BASE jumpers / adventurers are a special "sub-section" of the human race. It is in our nature to push our limits, have fun, play a bit of Russian Roulette, go lower, do one more somersault, jump in wind, use the wrong gear, etc. You know what I mean.

I have done it. I think that 99% of jumpers have consciously or subconsciously said "what the heck, it does not feel right but I'm going for it anyway". This ups the excitement, etc. It also elevates the risk. This is when BASE jumping actually changes from a risky activity (like everything else we do in life) to a dangerous activity. Because we have decided to make it dangerous. Not because it is!!!!!
Some examples:
FLYING - you've just finished your training and you are doing a cross country flight. You decide to fly low over tiger country to impress your date. Trees and mountains everywhere. You have never really practiced STOL's and forced / EP landings apart from a few "artificial" landings during your license test. The engine splutters. There is a field about 50m long. You aim for it. . . . Your odds?????? Now, if you had of practiced those landings during your training, chosen an aircraft that can side slip like hell and is designed for STOL, and you followed the rule of flying from field to field (i.e keep landing areas/outs withing range), what are your chances now??????
BASE Jumping - you've done your course at the Bridge. Then you decide to jump a gnarly underhung cliff with a tight landing area and no outs. You over-rotate (no real training in aerials), you open low, you can't get the maximum glide efficiency out of your canopy to make the landing area (you didn't really learn the intricacies of flying canopies and aerodynamics), you . . . . . . are in trouble ......... Decisions, decisions. . . . . . . . .
The reality is that you can encounter situations where you have done your utmost to be prepared and make the right decisions, and something still goes wrong. But this scenario is rarer than you may think.
It's your decision!!!!!!!!
p.s. There are a number of people around the world that collect and study BASE statistics. Guess what? Virtually ALL accidents have some degree of human error involved. This is easy to say in hindsight. How do you overcome or minimise the impact of this problem? What is the magic secret?
There is no magic.
Follow the often repeated advice of: good training, good mentor, great gear, take it a step at a time, be realistic, if you want to aim high - that is fine - but make sure you travel the road there - don't just go from thought to final act in one step, respect the sport, respect YOUR life.
As you said, this will cover a very high percentage of potential accidents. You can never stop all accidents, but you should certainly make an effort to minimise them.