Making gambling a part-time job is already risky. How can you think of making gambling a full time job and talk about a career in gambling? Gambling is a business but that is only for bookie and casino owners. Players are people who are willing to spend money on betting. So players cannot make gambling a job because from the start gambling is just a game and you can get addicted to it and harm you and your family. I think I need to provide an illustration that can make you think again about your idea.
Gambling shouldn't be a career choice, gambling should be an activity we do for entertainment and not to make money. The money part of gambling that you can double your money should be seen as a bonus. Winning when gambling doesn't happen all the time therefore you can't depend on gambling as a choice to make money. If you depend too much on gambling, you're going to get addicted and this will become a problem for you as you'll spend all your money gambling without benefits.
You can make money from gambling then that money should be invested into a businesses that'll generate more money for you as gambling isn't a job that'll pay you everytime. Professional gamblers also have other jobs that they depend on for getting money and gambling is just used as a side activity to support their main income. Having to rely on gambling for money would make you not to have direction.