There’s still some gamblers that manage to become successful with their gambling career through skills. There are games like poker that give you a high percentage of winning if you are good probability and psychology skills.
Also there’s sports betting pro that doing calculated bets by betting using arbitrage bets that gives sure profit no matter what will be the outcome of the game. And some people are just really good in sports analysis. On gambling games that requires skills to win offers a consistent winning possibility.
Success is really impossible if we will just consider pure luck based game like slot and table games.
Gambling success may be impossible even if they have skill and high probability in sports gambling and other types of gambling, but some gamblers have a history of a high ratio of wins compared to losses so that some gamblers can be said to be successful based on calculating the win ratio, but gambling still has a high risk of losses that are not published , so never judge the success of other gamblers but increase vigilance in betting levels and you have to manage your finances in gambling, make sure you use money that you are ready to lose in gambling.
I think we are just talking about possibilities here and not a guaranteed success since the word guarantee is not applicable on gambling. I follow many successful poker player like Daniel Negreanu and many more that has a high success rate on poker. High success rate or high winning percentage is the only metrics you can use to determine success on gambling since you already mention that’s risk is high on gambling.
I’m not talking about guaranteed success here with skills but a high chance to become successful on this gambling category if you have a very good skills set that can dominate other players or bookies odds placement on sports events.