Like why do they care how many times I go to porn hub every day or that nothing gets me harder than a free use MILF? Why do they care that I don’t know how to spell consistency so I have to Google it every 3 months.
What the fuck is wrong with people?
They are interested in your data because you are human and you do human things, the more they understand you and your activities the better they can gather knowledge for economical decisions such as Ads, Trends etc.
Most commonly they use this information to manipulate you into using their services or changing your preferences by marketing and Ads. The more they understand you the more effective it is.