It's not obvious that the best way to reduce existential risk is to actually work on the problem. Imagine if every farmer put down his plow and came to the university to study artificial intelligence research. Everyone would starve. It may well be that someone's best contribution is to continue to write software to do billing for health insurance, because that helps keep society running, which causes increased wealth, which then funds and supports people who specialize in researching risks among other fields.
I suspect that actually, only a small percentage of people, even of people here, could usefully learn the political truths relevant to existential risk mitigation via the kind of discussion you are proposing. Very few people are in a position to cause political change. The marginal utility gain for the average person to learn the truth on a political matter is practically zero due to his lack of influence on the political process. The many arguments against voting apply to this question as well, of seeking political truth; and even more so, because it's harder to ascertain political truths than to vote.
Most interest in politics is IMO similar to interest in sports or movies. It's fun, and it offers an opportunity to show off a bit, gives something to talk and socialize about, helps people form communities and define their interests. But beyond these kinds of social goals, there is no true value.
Most of the belief that one is in a position where knowing political truths is important, is likely to be self-deception. We see ourselves as being potentially more important and influential than we are likely ever to become. This kind of bias has been widely documented in many fields.
To me, politics is not so much the mind-killer as the mind-seducer. It leads us to believe that our opinions matter, it makes us feel proud and important. But it's all a lie. Politics is a waste of time and should be viewed simply as a form of entertainment. Now entertainment can be good, we all need a break from serious work and politics may be as valid as any other form of recreation, but we here should recognize that and not inflate its importance.
The arguments against voting are mostly puerile, and so is this one against political judgment. See here for an alternative view.
Can we talk about changing the world? Or saving the world?
I think few here would give an estimate higher than 95% for the probability that humanity will survive the next 100 years; plenty might put a figure less than 50% on it. So if you place any non-negligible value on future generations whose existence is threatened, reducing existential risk has to be the best possible contribution to humanity you are in a position to make. Given that existential risk is also one of the major themes of Overcoming Bias and of Eliezer's work, it's striking that we don't talk about it more here.
One reason of course was the bar until yesterday on talking about artificial general intelligence; another factor are the many who state in terms that they are not concerned about their contribution to humanity. But I think a third is that many of the things we might do to address existential risk, or other issues of concern to all humanity, get us into politics, and we've all had too much of a certain kind of argument about politics online that gets into a stale rehashing of talking points and point scoring.
If we here can't do better than that, then this whole rationality discussion we've been having comes to no more than how we can best get out of bed in the morning, solve a puzzle set by a powerful superintelligence in the afternoon, and get laid in the evening. How can we use what we discuss here to be able to talk about politics without spiralling down the plughole?
I think it will help in several ways that we are a largely community of materialists and expected utility consequentialists. For a start, we are freed from the concept of "deserving" that dogs political arguments on inequality, on human rights, on criminal sentencing and so many other issues; while I can imagine a consequentialism that valued the "deserving" more than the "undeserving", I don't get the impression that's a popular position among materialists because of the Phineas Gage problem. We need not ask whether the rich deserve their wealth, or who is ultimately to blame for a thing; every question must come down only to what decision will maximize utility.
For example, framed this way inequality of wealth is not justice or injustice. The consequentialist defence of the market recognises that because of the diminishing marginal utility of wealth, today's unequal distribution of wealth has a cost in utility compared to the same wealth divided equally, a cost that we could in principle measure given a wealth/utility curve, and goes on to argue that the total extra output resulting from this inequality more than pays for it.
However, I'm more confident of the need to talk about this question than I am of my own answers. There's very little we can do about existential risk that doesn't have to do with changing the decisions made by public servants, businesses, and/or large numbers of people, and all of these activities get us straight into the world of politics, as well as the world of going out and changing minds. There has to be a way for rationalists to talk about it and actually make a difference. Before we start to talk about specific ideas to do with what one does in order to change or save the world, what traps can we defuse in advance?