Even though there is a fair amount of nonsense in Durham's report even he has now stated that the FBI had solid grounds for opening the investigation. For reasons that only he can explain he buried this finding on page 295. This finding is consistent with the findings in other reports (Horowitz, Mueller, Senate Intelligence Committee). It bears noting that this investigation (known as Crossfire Hurricane) was of Russia and its attempts to influence the elections in 2016. Trump himself became the subject of a different investigation (authorized by his own Justice Department and led by Robert Mueller) after he fired Comey. In an interview he gave the following explanation for firing Comey:
"I just fired the head of the F.B.I. He was crazy, a real nut job. I faced great pressure because of Russia. That's taken off."
Unfortunately for him, the move had the opposite effect and it turned out there were quite a few things regarding contacts between his campaign officials and family members and Russians that he would have preferred not be looked at too closely.