Need to be lucky to have profit in long term. Few gamblers can have this profit, most gamblers will lose money, it's inevitable. The casino needs to make profit and if players don't lose money they won't earn money.
For me it's not a good idea to try making this profit, there is a very low chance to become one of the few rich gamblers and I don't want to lose much money trying this.
Luck and skills combined, it's a long journey and luck alone would not help you to be successful. By choosing a game is always vital, of course you should choose a game which you think you have the advantage and your passion is on it. I believe focus is very important too, you do not have to play different games if one game is giving you good return, and along the way you have to adjust as they are watching you for sure.