Gdpr relates to data that can be used to identify you. Your username and content associated with it is not identifiable,so they are free to share it. Plus you agree to the sharing of that data when you sign up. Anything thst explicity ties your username to identifiable information such as email, ip, other usernames etc is controlled by Gdpr.

The goal short term isn’t to be profitable though. The goal is to pull enough users so they can effectively stunt the growth of ‘competition’.