I disagree that jack0fnone is mentally ill. I see him as a 14 year old. It's perfectly understandable that a 14 year old might go through a bitcoin phase, be awestruck by gwern.net, daydream up these crazy ideas.
Kids go through crazy phases and still mature into stable, reasonable adults.
Edit: To me, the writing style seems very teenager-ish as well, though I don't have a good baseline for mentally unstable writing.
It struck me as someone who was earnestly trying to appear more educated than they are, or someone who'd recently (re)read "A Confederacy of Dunces".
That said, the thought occurred to me that it might be someone aware of how easily one would otherwise be able to match up their linguistic patterns and identify them to another online persona, and that perhaps they were actively trying to combat that.
The former scenarios are completely contrary to the former, and it shouldn't be forgotten that this is all very recent, and not something that concluded years, months, weeks, or even days ago, so it's possible we haven't seen the last of it.
The delusion that many people are actually one person recurs in mental illness, there's probably even a name for it.
Coupled with insecurity, it might lead to paranoia and feelings of persecution by a powerful puppet-master. Here it seems paired with grandiose delusions, perhaps because the person is otherwise intelligent & high-functioning, or using drugs which create a sense of invulnerability. Either way, there are strong indicators of mental illness.
I would put joking (or trolling) as-if-mentally-ill as a second-place possibility, and teen-daydreams as a third-place possibility. But maybe all three in different proportions.
It's possible (personally I don't think it is likely) but either way I think that it is best to not engage with this person. Either they are a teenager who has some learning and growing up to do, or somebody who needs to be treated.. but the end result is the same.
Kids go through crazy phases and still mature into stable, reasonable adults.
Edit: To me, the writing style seems very teenager-ish as well, though I don't have a good baseline for mentally unstable writing.