There's a saying that's been around for a long time:

History is written by the victors

This saying sounds true, but it really isn't true anymore and honestly may never have been true.

In an age where literacy rates are very high the number of people who can write something has gone up a lot.

In an age where publishing has got exponentially cheaper the number of people who can afford to disseminate their written works has gone up a lot.

In an age where information technology allows information to flow across the entire world in seconds the speed with which information can flow has gone up more than anyone in the past could ever have imagined. More than just the speed of information flowing there's the ways in which information flows across borders with ease. The idea that someone inconsequential from the "loosing side" could publish an idea that the rest of the world could see within minutes was an unthinkable idea just a few generations ago. So easy is it for information to flow these days that even highly technically proficient superpowers have trouble censoring the internet because the costs of transmitting information have become so low.

I propose a different saying:

History is written by the historians

Even before modern technology combined with a highly literate populace changed everything about publishing, this would have been a more accurate saying. Even in the past the majority of people had no desire to engage in the effort of writing historical documents. Writing about history tends to be something that is done at great expense to the author. Many of the elites were never authors, they may have had writers that they supported but the act of writing is not one that tends to make people rich and powerful. The rich and powerful almost always have better things to do with their time than to write works of history. Even with the costs of publishing dropping so much writing history for the most part isn't a profitable venture in most cases.

Sure there's a few areas where writing about history might pay well enough for the author to make some return on the time and energy that it takes. But mostly the motivations for writing about history seem less about money and more about contributing to something bigger than ones self. There's an emotional appeal to writing something that will outlive you. Well at least for the authors, without this I can't imagine that someone would engage in it.