Well, besides the fact that privacy violations are (should be?) against the law and unethical, there are a few considerations you could have.
The one that springs to my mind right now is: Knowledge is power; which is also true in that case: the more an entity knows about you, the more power it has over you. And not only blackmail, but recent hints (AI-powered election meddlings, addictive user interfaces, etc.) have proven that your instinct can be, and will be used against you, whether you are conscious of it or not.
And of course, there are problems linked to physical security (if the wrong person can see you're spending a week abroad, your house might be broken into, or worse).
Let's not dwell on the ethics of financing a company that sells your personal data.
Private data is by definition not supposed to be made public, it is sensitive.
Treat it like an attack surface: the more there is out there, the more likely it is that something can be used against you.
The one that springs to my mind right now is: Knowledge is power; which is also true in that case: the more an entity knows about you, the more power it has over you. And not only blackmail, but recent hints (AI-powered election meddlings, addictive user interfaces, etc.) have proven that your instinct can be, and will be used against you, whether you are conscious of it or not.
And of course, there are problems linked to physical security (if the wrong person can see you're spending a week abroad, your house might be broken into, or worse).
Let's not dwell on the ethics of financing a company that sells your personal data.
Private data is by definition not supposed to be made public, it is sensitive. Treat it like an attack surface: the more there is out there, the more likely it is that something can be used against you.