I think you can win in gambling or be a legend in gambling but you can't success in gambling because it is a game not a life achievement.
How can someone become a legend in gambling if he's not going to become succesful with it?
if someone becomes successful in gambling, is it an achievement or not?
If I can make millions in gambling, I can consider myself successful, true it's just a game but you can make big money here, and that's a big success we all wanting to achieve.
I'm emphasizing what he said that you can't become successful in gambling because that isn't a life's achievement.
This can also be applied for other types of success, if someone becomes successful in any other means like in the gaming industry, he won't consider that as a successful thing.