And if you are talking about luck then you should consider have enough balance to recover your loss with 50-60% winning chance because of the house edge you can't play as 50% chance. There is not 50% chance of winning that could double your win because there is house edge, so by using 60% chance and enough balance will give you decent profit
Gambling is and will always remain about LUCK.
Your belief will reflect your actions towards gambling, by believing that it's purely luck that is needed to win you are taking your chance to become a professional gambler. Yes, professional gambler believes in luck but does not rely on it to win, they are matured already in gambling due to their long experience and they believe it is the skills and knowledge which is the only key to win in the long run.