1) She still led in the polls after the release of the FBI letter. The FBI's decision to review previously-unseen emails on Huma Abedin's laptop didn't push Trump ahead in the polls.
2) Nothing in the emails leaked by Russian state-run media was particularly scandalous. Millions of Clinton voters didn't abandon her because Donna Brazile tipped her off about debate questions. Looking at the polls, no one cared.
3) What destroyed voter confidence in Clinton was her use of an unsecured, unauthorized email server. That was revealed last year by the House Select Committee on Benghazi, not the FBI or Putin. It prevented her from ever overcoming her reputation for being shady and paranoid.
4) Clinton's lead in the polls was real, and she never lost it. She led in the polls by an average of 3.2%. Despite the Russian email leaks and the FBI "reopening" her email case, she still topped Trump by 2.0% in the popular vote. Polling numbers within 1.2% of the vote totals is remarkably accurate, and proof her support didn't collapse in the final week.
Clinton lost for one reason. Her campaign pulled resources from battleground states to run up turnout other states, despite warnings from staff on the ground her lead there was fragile. The millions of additional votes she created were rendered meaningless by the several hundred thousand she lost in states where it flipped electoral votes.
She thought she had the electoral vote sewn up and put all her chips on boosting Democrat turnout in other states to lengthen her coattails. She bet wrong. That wasn't the FBI or the Kremlin, that was Brooklyn.