Yes, anything can happen in gambling, just like a $2 lottery ticket can win millions dollars, so it's possible to win the amount stated on OP.
However, reproducibility is an entirely different thing. He can win doesn't mean he can teach or can repeat the winning.
Anyone says they can teach you to magically turn $5,000 into $1,000,000 is going to scam you. Why? Because they will spend their time gambling, not teaching or selling products.
I agree with this statement. Truly, anyone claiming such numbers is really fishing for the weakest of the weakest minds. The chance of making 5k into millions is mathematically extremely low.
Also why would anyone trust someone else's claims with such large amounts of money? Im sure the spreadsheet looks nice and everything and may even have robust data but some things are too good to be true. Otherwise everyone would be millionaires...
If all can do the same, then we won't see any gambling house that still open or still surviving, right? But we don't really know the real score if things happened then congrats to OP if not, no one force anyone to believe though, whatever you think it's your judgement and OP don't need to care about it, it's our opinion against him.
Maybe there are people who know well. They managed to create a good system that helps them to anticipate or predict the possible outcomes.
Who knows in due time you also find the secret pattern,
kidding aside, we all, as gambler desire to win, but most of us are losers