>In most cases, commercial entities that reuse Wikimedia content at a high volume have product, service, and system requirements that go beyond what Wikimedia freely provides through publicly available APIs and data dumps.
https://commons.wikimedia.org/wiki/Special:MediaStatistics
This MediaWiki special page is also available for other wikis; the English Wikipedia itself hosts 152 GB of files that were uploaded there instead of to Commons for one reason or another (e.g. non-free material under fair use).
https://wikitech.wikimedia.org/wiki/Event_Platform/EventStre...
If someone shops around for some product, then visits a Wikipedia article related to it and then buys something, you can maybe infer which qualities of the article or what information made them choose. That again, you could try and sell to advertisers as a service.
I'm pretty sure that Wikimedia would never sell such a service.
This is about access to content and network resources. Definitely not about access to user's browsing histories.
In my experience, user privacy is taken very seriously by Wikimedia's staff and leadership. The privacy policies/practices[1] are top-notch and not just a gesture or PR/appearance management.
[1] https://wikimediafoundation.org/news/2018/05/21/wikimedia-fo...