This sums it all up. Gambling isn’t a job. On occasion, one can win some some money here and there but as it doesn’t come regularly and at a certain time and no one literally employed you, it just cannot be said to be employment.
And then talking about starting a career is out of the question. A job is supposed to pay you for your time or/and services rendered without you requiring you to part with your money. With gambling, you part with some money hoping to win and can still end up losing. Gambling simply isn’t a job.