Consistency, winning percentage and length of gambling career is the main factor which I consider needed to be a professional gambler. It needs to be the combination of the 3 since it determines how successful gambler on a game that has risk involved.

It’s very hard to maintain that 3 factor by relying only luck since it requires skills to become consistent on having profit in the long run.

The only way it can possibly achieve os through playing skill based gambling games only.