For scammers like Robin, I am sure he has many strategies. That is just one. I believe this kind of betting scam which provides tips and eventually sells subscriptions are not simple efforts. This is probably a big operation. It is not difficult anyway because you are mostly just sending automated spams. It is usually done through emails, social media, messaging apps and channels like Telegram, even forums like bitcointalk.

There is also a simple formula. Send tips. If wrong, start again with a new account. Repeat until you can make a short win streak. And then sell subscriptions.