This is from the website learninternetgrow.com:
Con: Selling User Data
As a website owner, you have a certain responsibility to either protect your users from privacy violations or make them aware of these potential violations. So it’s important to understand that when using Disqus on your website, you’re condoning the selling of your users’ data.
Disqus does make money from their Freemium pricing structure, but just like so many other social platforms, the big bucks come from mining user data and selling it to third-party advertisers.
To learn more, click the image below to jump to Disqus’s privacy policy.
Disqus Privacy Policy Image Link
Here is how they do it.
Once you sign in to Disqus as a commenter, Disqus gains the ability to track you across different websites (keep in mind that you don’t even have to make a comment for this to happen).
Tracking you provides them with valuable data, such as,
browser cookie data
IP addresses
location
add-ons
device identifiers
So if you sign into Disqus, comment on a rock climbing blog about losing some of your gear, then trot on over to a vegan cooking website and browse some recipes, you might soon see a targeted ad for vegan energy bars.
I've used disqus for years and nothing like that has ever happened to me.
I have a few accounts each with their own email. I've never got spam or ads sent to my email address.
I know without adblocker they include ads but AB blocks them.
99% of websites track cookies. It's the way of the web.
If they're collecting my data they're likely bored with the results.