It is just another spammer - not a hacker, just someone who is using a list of social media sites as his/her bulk emailing marketing list to fire off ads to. They probably bought the list off someone else and are hoping to make their fortune from selling their illegal services to all of us grannies who they think are old and decrepit.
They don't need to hack their way in - they just join as if they are old grannies too, and post an ad a minute until they are deleted and banned. Don't encourage them by replying on their threads, just report them to GN and then ignore them. They are no danger to anyone else (unless you buy from them and risk telling them your bank details.)