Publishing has always been a controversial industry. Its history of banned books, lawsuits and angry letters wouldn’t look out of place in the most far-fetched of novels. And publishers have to strike a delicate balance between publishing books that are important for artistic, cultural or social reasons, and those that will sell and support the important books that won’t.

When they’re criticised for what they’re publishing, publishers will defend themselves on free speech and commercial grounds. And when they’re criticised for what they’re not publishing, as they have been in recent years over the lack of diverse authors, they turn to the commercial argument again: it won’t make money, therefore we won’t publish it.

The news that Katie Hopkins and Milo Yiannopoulos were writing their memoirs prompted much soul-searching in the world of publishing. Both books reignited a familiar debate over the balance between defending free speech and giving a platform to hate speech, and both have been defended on the grounds of freedom of speech and straightforward commercialism.

But does hate really sell? I’m a planner for an international communications agency, and I used the tools of that business to assess the market size for both books. The results were surprising, and, for someone whose belief in the goodness of people has been tested over the past year, encouraging.

Let’s tackle Hopkins’ book first. She may be a high-profile figure, but my data suggested her book could be a tough sell. When I filter for those people in the UK who align with Hopkins’ anti-equality, anti-diversity worldview using the planning tool Global Web Index, I see a possible audience of 1.2 million people. That’s out of a total UK adult population of around 44 million.

If every one of these people bought her book it would be a huge success, but this audience is also significantly less likely to see themselves as a “reader” or to buy books than the average person. For example, a third of UK consumers bought a book in the past month, compared with just a quarter of people who actively disagree with the idea we should all strive for equality.

There are also a lot of more prosaic demographic reasons – her potential audience is more likely to be male, less likely to read online news or buy products via the internet – that would make getting this book into readers’ hands an uphill battle.

A similar picture emerged when I looked at the US, and the audience that Yiannopoulos might have attracted if Simon & Schuster hadn’t cancelled his book. The data indicated there are 7.1 million people in the US who align with Yiannopoulos’ anti-equality worldview. This feels like a scary number, but this audience is even less likely to read for pleasure than its UK equivalent – just 11% had bought a book in the past month.

One thing that perhaps shouldn’t have surprised me about this audience, given the result of the 2016 presidential election, was that a lot of his potential fans were college-educated, and many earned high wages. It looked to me as if fear of diversity has more to do with attitude than economics. Nevertheless, they were still tremendously difficult to reach if you wanted to sell them a book.

Hot air and controversy certainly fuels social media and fills column inches, but there’s scant evidence it makes people part with cold, hard cash.

There is, however, some positive news. When I looked at this issue from the other side, I was able to identify a huge number of people in the UK with a progressive, pro-diversity and pro-equality worldview. There are 11.4 million adults here in the UK today hungry for stories that represent the Britain they live in. Even better, these people are comparatively easy to sell to. They identify books as one of their main lifestyle interests, they buy books regularly and many of them can be very efficiently reached through social media.

I call these people “readers of diverse books”, and they are 10 times more numerous than the people who subscribe to Hopkins’ view of the world.

In business it’s all too easy to justify a cynical decision with the defence “but it makes money”. Yet in this case, if you look at the data, it’s not true. There is more money to be made from publishing hope not hate, so let’s do the right thing and publish more diverse books.

• Source for all data: GlobalWebIndex Wave Q4 2016