Dear Robert,
A well written and interesting essay on the subject of existential risk and why we should care. Although I only touched on the topic of artificial intelligence in any depth, I enjoyed the broader scope of your essay. It is true that new technologies you mention hold great promise and peril and will most likely either end up being a solution to our problems or making them much worse depending on how they are used. AI in particular is difficult as it will literally have a mind of it's own. I agree too that become a space-fairing species is the only long term solution to our survival, hopefully SpaceX and similar organizations can help accelerate that development to the point where space travel becomes profitable, economical and sustainable (rather than mostly government funded).