The question is, would she have lost had Dir Comey not re-opened the investigation???? Remember ... the entire campaign, to the last person, thought Mr Trump would not win as late as election day ...
No, she wouldn't. Without the Comey letter she would have won.
But without the Bernie or Bust crowd she would have won.
Without the help from Putin for Trump she would have won.
Without sexism she would have won.
Without her idiotic failure to campaign in the Rust Belt states she would have won.
Without her nincompoop of a campaign manager she would have won.
Without the racism and xenophobia of Trump supporters she would have won.
Without the disillusionment of the Rust Belt blue collar former Democrat workers she would have won.
Without her unforced errors such as saying to Wall Street investors that she had one opinion for them, another for public consumption shw would have won.
Without Wikileaks she would have won.
Without the enthusiasm gap in her campaign vs. Trump's she would have won.
And so on and so forth.
When you lose by a grand total of 80,000 votes differential in three states (and remember, she needed to only flip 40,001 of those to win) ANY of the above factors is a decisive factor.
Sure, we can say that Comey's letter was one of the biggest factors... but even WITH Comey's letter but without the Bernie or Bust crowd, she would have won.
And so on and so forth.
Only the confluence of ALL the above factors and whatever else I forgot to mention, gave Trump his victory. So each individual factor is decisive.