That is an amazing profits, well I wish him all the best in future bets, I guest persistent and smart gaming skills made this huge winning possible. I wish I could learn some of his techniques.
If you achieve very high multipliers at bustadice, for example, this has nothing to do with the fact that you are particularly good at the game, but you are simply lucky. The more games you play, the higher the probability that you will get such a lucky punch once. Here, of course, scripting options, such as those offered by Bustadice, help a lot. However, you should not forget that you lose a lot of money on the way.
So in the end it comes down to pure statistical probabilities.
Or to put it differently, the more games you play the higher the probability that you will get a single bad streak that ruins an overall path of winning streaks (where the user tends to believe the strategy works).
In the end, the house wins and the bankroll is the only source of reference for that.