I am sure that when you heard his story, you are amazed to him and I think you imagine if your luck will be like him. Winning 1 bitcoin in gambling is difficult for every people and only people who have the luck that can do that. But that is not good if we are only playing gambling because we chase the win money, we need to do other things to get the money and not from gambling.
Winning 1 bitcoin depends on when it was. Though 1 bitcoin = 1 bitcoin but for me the price by that time is also important. The guy never said when he was able to met that person who told the story of winning 1 bitcoin on roulette. But as long as it's a success for him, then let's just consider that guy as a successful gambler. I'd like to take an hypothesis that the guy won 1 bitcoin on roulette + trading during the all time high days of 2017.