Last year, I took part in crowdfunding a ventilator for intensive care for Covid-19 in Brazil. I believe it was a mistake - I'd better have donated to GD. Of course, hindsight is 20/20, but I learned from this experience that I underestimated relevant points:
a) I wanted to feel important;
b) I gave a great weight to the fact that EA and rationalist friends (people I usually trust) were doing it, too, but I neglected that we were probably being affected by the same biases;
c) None of us had previous experience in funding similar risky projects. However, we did analyze their credentials, and we had someone who understood ventilators and said that, though the project wasn't as impactful as we first thought, it was likely still worth funding - because funding for research totally vanished in Brazil.
d) my direct interaction with the team asking for funds probably made me overestimate their case;
e) Everyone was doing similar projects back then. I took it as a sign that it was a good idea. I was so wrong: I didn't realize the context had changed - the area got way less neglected, it attracted people whose projects were in other areas, or that usually wouldn't be worth funding, and the low-hanging fruit was already being picked by large donors.
My point is that I failed to update my priors. If someone shows up today talking about how they can save thousands of lives in the next pandemic by lowering the costs of this particular medical procedure, they probably have thought about it deeply (possibly passionately) and put some skin in the game; they might be overestimating the general risk, but not so much their ability to deliver the product (before others do). If they do this after the pandemic started, they are (if not a total maverick) likely someone who used to do something else which is not being funded anymore because everyone is focused on the current catastrophe.
Concluding, though I still think there are impactful "weird things" that only I can fund out there, they are mixed with lots of bad fruits, and I'm rarely particularly skilled in telling the difference - actually, I realize that I might be particularly bad at doing so when some emotions get involved. I became an EA, and routinely check this Forum, not because I hope someday to be as impactful as Dustin Moskovitz, but because I can share this epistemic burden with others - or just outsource it to an expert I might trust.