In the nyt palace intrigue story - which is crazy - btw, trump comes off as a toddler.
https://mobile.nytimes.com/2017/05/10/us/politics/how-trump-decided-to-fire-james-comey.html
If there is Russian collusion it seems like it's all around some of the people close to him, the story identifies Stone, Kushner, Pence, McGahn as being "supportive" of the "idea" of firing Comey and Bannon and Priebus as not being supportive, for obvious "optics" reasons.
He also discussed the idea early with his thug nypd agent zero bodyguard Schiller, which is just insane, to me.
So trump did it, and Sessions was obviously on board fully.
It's more than possible that trump is just insane and doesn't really realize how the Russians helped him, and doesn't consider Russian cash as any big deal, but the people on the trump train are using him as a human shield: directing his tantrums into actions that might delay their own demise.
Comey got fired after asking for more resources to accelerate the investigation but none of that was mentioned in this palace intrigue story. It may have triggered the firing, and trump maybe wasn't even aware of it, he migt be operating on a much lower level of brain activity, ping ponging off the tv, aides, and their own agendas.