Of course, Mueller’s team would have loved to have taken down Trump, but the more achievable goal was to misdirect attention from their own actions. The probe was initiated and staffed by the same people who prior to the election sought to use the mechanisms of the law enforcement bureaucracy to deny Trump the presidency.
Sigmund Freud called it “psychological projection,” whereby the human ego defends itself by attributing one’s own negative traits to others. That is how a group of high-level bureaucrats and prosecutors convinced themselves that Donald Trump had no regard for democratic norms and that he was a traitor in the embrace of a foreign power, allowing them to answer “a higher calling” by illegally intervening in the election.
The overwhelming probability that Trump would lose the election provided an assurance that they were right about Trump because they thought most other Americans were seeing the same thing. It also provided a sense of security that they would never get caught and would be advantageous to the careers of each. Hillary’s underlings were well aware of the breaks they were being cut, especially in the form of phony plea deals that protected them from criminal liability.