I also think that the guy has just made up a story to promote the site. I don't think that anyone could get around $30k by just sharing a link on social media and leaving it for months, and once they check it again they have earned $30k without even knowing that. That's totally made up story and the poster should learn fictional writing because he can generate more income by telling fictional lies rather than promoting such sites.
He's directly promoting that website with the help of a simple made up story, and who knows many people might join that site as referrals after falling to his story. I'm 100% sure that earning referral income without doing proper marketing is close to impossible and anyone who claim such rewards is just misguiding the users.