IANAL, but this isn't really a legal question. It's a question about why it seemed like Reddit was (and tends to be) so wrong when it comes to predicting the outcome of any sort of political event. As a former first lady, senator, and current presidential candidate, I hate to say it, but Hillary is as "above the law" as a person can get in this country; making this more of a political question than a legal one. I've been using the site for 8~ years, and this is what I've observed when it comes to Reddit's views on politics.
Reddit (in general) eschews main stream media. Users of Reddit tend to be of a demographic that is annoyed by the partisan nature of mainstream media, particularly the 24/7 cable news cycle. There's nothing wrong with that, and I feel it is a valid criticism. However, when you're not watching CNN, Fox, etc., you're not allowing yourself to really see "the message" that's being put forth by any of our political institutions. Anyone who has been watching MSM and seeing how this email scandal (and the entire election) has been presented to the American people would tell you that it's very likely that Hillary won't be indicted, and that she will go on to be the next president. I personally feel that there has been far too much protection of Hillary at every level for any other outcome.
Reddit is an echo chamber. A very small minority of users actually submit content (comments or links) to the site. Most are here to lurk. Anytime you read anything on Reddit, you're reading the words of a small, often highly partisan minority of people who care enough to register to the site, log into the site, and submit their thoughts. This is a form of selection bias, because there is some inertia that needs to be overcome in order for someone to even voice an opinion here. The comments you read here are often of people who have a strong opinion one way or another, and therefore have some amount of vested interest in either outcome (indicted vs. cleared, for example).
Reddit users tend to be more tech savvy. I work in IT. The words "private email server" do not mean a lot to your average person. Most are not even aware that there are email servers, they think of it as another form of mail. So an issue like hosting a private email server containing classified information does not trigger the public outrage in the real world that it does in a place where the majority of us spend way too much time on the Internet. Indicting a presidential candidate is a big deal. If the FBI were to indict the wife of a former US president, there is significant risk to the careers of everyone involved, especially if she later went on to win the election. When her only opponent at this point is Trump, that's an enormous gamble to take; and it's certainly not a gamble you take when the American people seem largely apathetic compared to a place like Reddit.
Ultimately, what you're witnessing in this election cycle is a disconnect between the comments you're reading on Reddit, and actual reality. This is not new, and it's likely going to repeat itself in the next election cycle. Regardless of your opinion of newspapers and TV news, I think it's important to keep these sources in mind when attempting to get an idea for the political climate. The email scandal, while technically a big deal, was not big enough of a deal to the general public for anyone at the FBI to risk their job over.