In a norm, I don't believe someone who has made such an amount of would even want to review such information he would rathe want to continue milking the betting platforms codedly than wants to letting people know of it, and besides who wants to share this kind of information which may hurt his source of income if many people are found doing same thing.
I agree with you that this is a potential scaming trick.
The forum is free and so creating this kind of thread is fine as long as you are not screwing any user. As the OP said, he is not selling anything but of course, he may be has hidden agenda why boast such winning numbers to gamblers here. Also, I can agree with you that if he is indeed earning tons of money by his strategy, why not use such strategy as much as he can and profit from it? With huge money in his pockets, do you really think he still has time to make a discussion here?
You raise the logical point that people who bet with such amounts or who are involved in such activities have the opportunity to spend their time like this on the forum. I think not. But I won't tell him if he is that kind of person or not. But my question which you also asked is that if he has the opportunity to earn money through fixed matches then why doesn't he do it or why is he promoting others? No one does anything without a motive. So I also suspect that he may have tried to convey something different. But everyone who is a user on the forum should know what to do and what to avoid.