Gambling is gambling, if anyone is able to predict how much they will make out of gambling by so so year and it happened then they have their ways around it.

1. There is a chance that he is cheating the gambling system, because you can't be so sure of your outcome until it happened but in his case he said it before it happened.

That's supper suspicious

2. He is a rare lucky man, this is a very slim chance when gambling and this lucky doesn't always last longer.

3. He made a lot of money once or twice and use the fund well.
There are few cases of successful gambling that turn things around for good.