His message is very self-centered and does not mention other people (joining him or helping him reach his goal). It is not unreasonable to think/realize that his belief is/was failing to fit with his socio-cultural background, especially considering he was mostly running the op alone.
There were mentions of admins that were paid lowly sums compared to what he was making, I assume they had very limited attributions and he was the only one in true controlling capacity.
Throw in the necessity for secretiveness due to the nature of the op, the ensuing distrust and suspicion and it is a safe recipe for psychosis as a result of stress.
I haven't heard anything about that. Are you referring to the fake cocaine that the undercover agent sold to a SR employee right before arresting them?
And no, there has been no report of any drug seizure to accompany the arrest of Ulbricht.