My guess:
Brennan went to to Moscow to find out what the FSB had on Trump. He would have known the Russian leadership for years and probably has a good relationship with his counterparts.
For all the tension between Obama and Russia over things like the failure of Russia to respect the LGBT agenda, the Pussy Riot imprisonment and so forth, Obama delivered for the Russians on the big items: not supplying lethal arms to Ukraine, not installing missile defense in Eastern Europe.
The Russians probably had very little dirt on Trump. (Likely nothing compared to what they have on the mystery-born Barry, the corrupt Hillary and sleazy Bill).
So the Clinton cabal decided to make up their own Russian dirt, and launder it through a cut-out their buddy former British spy Christopher Steele. In fact, it wouldn’t surprise me if the prostitute pee party was something that Bill Clinton once had, and they changed the story to apply to Trump.
One big tell that it was all a scam: When the FBI was handed the dossier, they didn’t seek electronic surveillance on Steele and Steele’s sources to find out exactly who in Russia were the ultimately sources — instead they sought electronic surveillance on the Trump campaign.
Bill Clinton as a POOR college kid also took a secret trip to Moscow.....hmmmm.....to meet his future BACKERS???