Trump ALSO didn't need to know the FBI had launched a COUNTERINTELLIGENCE op based on it.
1) Steele Dossier is a paid political product springing from Hillary's pocket
2) FBI launched a counterintelligence investigation into Trump's campaign team based on the Steele dossier allegations.
By May Trump had learned Comey was never going to tell him. Comey was actually being tested and he flunked the test.
Nobody is more vindictive than a narcissist who has his fantasy brutally destroyed. This entire book is an exercise in revenge against Trump for playing HIM.