Along these lines I am sort of skimming articles/blogs/websites about Lightcone, LessWrong, etc, and I am still struggling with the question...what do they DO?
Asking "What do they do?" is like asking "What do Hackernewsers do?"
It's not exactly a coherent question. Rationalists are a somewhat tighter group, but in the end the point stands. They write and discuss their common interests, e.g. the progress of AI, psychiatry stuff, bayesianism, thought experiments, etc.
(You're hearing about them now because these days it looks a lot more plausible than in 2007 that Eliezer was right about superintelligence, so the group of people who've beat the drum about this for over a decade now form the natural nexus around which the current iteration of project "we should do something about unsafe superintelligence" is congealing.)
Well, he was right about that. Pretty much all the details were wrong, but you can't expect that much so it's fine.
The problem is that it's philosophically confused. Many things are "deeply unsafe", the main example being driving or being anywhere near someone driving a car. And yet it turns out to matter a lot less, and matter in different ways, than you'd expect if you just thought about it.
Also see those signs everywhere in California telling you that everything gives you cancer. It's true, but they should be reminding you to wear sunscreen.
A lot of it seems rooted in Asimov-inspired, stimulant-fueled philosophizing than any kind of empirical or grounded observations.
And knowing this, you think that the only reason we could have to expect to create intelligence in a machine, even surpassing a human... is "Asimov-inspired, stimulant-fueled philosophizing"? That seems deeply unserious to me.
At any rate, my point remains. The flaws inherent to the current deep learning regime _absolutely_ disqualify them as being capable of any sort of rapid takeoff/escalation (a la paperclip optimization) that the rationalist community is likely referring to when they say super intelligence or ASI.
Sorry about the "asimovian" comment - you'd be correct to call it an exaggeration and somewhat toxic.