Content is volunteer, but I believe the company's infrastructure and software (I believe they use a modified MediaWiki based on an HN comment from an employee a few years ago) are all from a for-profit company. Wikipedia and the Wikimedia foundation are the non-profits you may be thinking of.

From the Fandom Wikipedia page (https://en.wikipedia.org/wiki/Fandom_(website)):

> The privately held, for-profit Delaware company was founded in October 2004 by Wikipedia co-founder Jimmy Wales and Angela Beesley. Fandom was acquired in 2018 by TPG Inc. and Jon Miller through Integrated Media Co.

But note that Jimmy Wales was a founder as well.

The content is created by volunteers. But fandom is a for-profit company. In its early days when it was known as Wikia, they maintained a fairly small team of people running the site. So they just had to make enough money for paychecks and bills. Here's my take on what went wrong. Throughout the years they grew. Because the company grew, they hired more hr people - more money needed. So they hired marketing teams, data science and so on. The costs skyrocketed. So now they're putting ads everywhere because they don't have that much more traffic than 10 years ago but the company is much larger.