Those involved in gambling and casino site promotion, especially those involved in team management, have their careers largely built around gambling and casinos. We can see their careers here as they get involved in gambling and casino sites and change their lifestyles as they get paid.
But not everyone can build a career around gambling and casino because not everyone is an expert in this field and gets regular profits. Only those who get expert and regular profit can make their career here.
The OP pertaining to play gambling as career not working for casino because you obviously don’t gamble if you are working to the casino because you have job description that doesn’t involve gambling.
You are playing gambling when you risk which is the one OP describing. Working for casino is truly the only way to become successful while you are still involved in gambling industry but again it’s not a gambling career but rather your job career in casino because you are not gambling on your job unless your job is to play with players and risk your own money.