I've talked about the zone of mediocrity in other contexts, but the idea is pretty simple. When you release an idea into the wild (whether it's a product or art or whatever) you are better served making a product that some people will love and some will hate than a product that is just OK to everyone. This is counterintuitive for a lot of us. It seems like making a product which is good but inoffensive will have the largest reach, but that overlooks the fact that people are less likely to engage with an inoffensive product in the first place.
The math is pretty straightforward. If 20% of people love your product and 20% hate it, you're going to get sales form at least 20% of the market, and probably more because enough people are invested in it (one way or another) to keep the discussion alive. If you can get up to 30/30? all the better. But if you make a product that pleases everyone, but excites (for good or ill) no one, then you're rolling the dice. No one will get excited enough to talk about your product, or to choose it over something they actually like.
It is at this point that an optimist wonders if you can make a product that 20% of people love but nobody hates. I admit, that's a nice thought, but reality doesn't work that way for one simple reason: the group of people who love your stuff and who hate your stuff are the same group of people.
This is a really hard thing for people to get their heads around. Fans are so passionate and enthusiastic that it's easy to take them for granted, at least until you piss them off. At that point, all that passion and enthusiasm turns against you. Look at any popular media - say, something (anything) Joss Whedon has done. When he takes a sharp left turn, the screaming will start on the internet and echo into the middle distance. These people who are so upset by whatever he's done are not people who were just kind of watching the show and suddenly became angry - these were enthusiastic fans who are now angry.
Even outside the small microcosms, this pattern repeats itself. Many people in the world have no particular opinion on Whedon but some people are, for all intents and purposes, anti-fans. They commit a similar sort of energy that a fan does to their disdain. They exist within the same cultural space as the fans, just with different Strong Opinions.
In a rational world, the assumption would be that these opinions exist on a spectrum. The haters might in time grow indifferent, then eventually come to like something, and vice versa. But this is not a rational world: the indifferent folks in the middle mostly just stay there, and the lovers and the haters hop from one side to the other without going through the middle.
Taken in a positive light, this is an excellent argument for why it's worth your time to be civil and pleasant to the the haters. They are more likely to turn a corner and become a fan than someone with no real interest in your product. I usually like to emphasize this positive point.
But it's also worth remembering the inverse. Your fans today at the people most likely to string you up tomorrow. I think almost every creator who has no responded to a fan's email promptly enough has had a taste of this. And it's easy for that to become paralyzing, but looked at the right way, it's kind of liberating. Fans are great. They are wonderful people and they have many benefits, but it's useful to remember that they are not the ultimate yardstick of your success.
That thing you made? The one that got the fans so excited or pissed off in the first place? That's the yardstick. Hang onto it. The alternative is to use the fandom as your barometer, and hopefully your grade school teacher taught you what happens when you do things just because the crowd thinks you should.
1 - Love and hate tend to come equal proportions. That's not always true, but it's not a bad rule of thumb.
2 - Ok, there's an exception here for people who love or hate your stuff for reasons that have nothing to do with your stuff itself, like book burners who take offense at a gay relationship in a book they haven't read, or fanboys from other media - the people who would buy a book if [PERSON THEY DREAM OF SEXING UP] writes it.
3 - Why are they angry? Artistic sentiment? Entitlement? Genuine offense? Answering that question is a post of its own, and one I really don't want to try writing.
4 - Or Abrams or Cameron or Wolf or Del Toro or Tarantino or King or Rowling or...you get the idea.
5 - In RPG terms, someone who bashes your game on a forum is still a more probable sale than someone who would never go to such a forum in the first place.