Gambling cannot be a career. Gambling is played for fun and entertainment. To relieve one's stress. It's not something to be made as a source of income. You can earn a lot by gambling, but that doesn't mean it's a job. Come on, man! Gambling means betting on something of your life. How can one bet on their life? They have to feed their family, don't they? If I were to make gambling my only source of income, then I would be the foolishest person in this world.
I would also add that gambling can be seen as hope.
Hope that at some point in the future things might be better if you are lucky.
That's what casinos provide, hope, for many people. It costs a lot of money in the end, but the effect on the brain is real.