Many people have the question - "How did you get my email?" Well, you can thank google for that one because it is crazy simple to do this. In fact there is more than one way to do this as well. There is software referred to as email extractors and then there are software that verifies each email. Ones that cannot be verified are discarded and you get the idea, your email is in the hands of some random person or company.
The second way is a sort of manual way, and this is again where google totally gives your data away for free such as your email and the steps are as follows. Pull up google and type as an example - Dating sites"@gmail.com" - It is preferable that you set google to show 100 results in the search rather than the default, which is much less. Once the results show up press Ctrl + A, followed by Ctrl + C and finally you will paste it here with Ctrl + Z, which is an online email extractor. It immediately differentiates between the random text and only takes out the emails with "@gmail.com" and nothing more. You can add any subject before that to reach even more email addresses and you can even change it up with "@yahoo.com" - "protonmail.com" and so on.
Above is what the extractor looks like and for a closer view you can click on the image to visit the site. The idea is that you may get a better understanding of just how NOT secure your information is. There are many tools like this and some do far worse than just take an email or phone number.
In short, google is a giant corporation and your privacy just isn't a major concern for them.