1 - The owner of the casino lives thanks to the profits of the casino, that is, he lives thanks to gambling
2 - Casino employees also receive casino salary, they live thanks to gambling
3 - Professional bettors also live thanks to the profit they make from the bets they place
These are literal responses lol but clearly, not the expectations that were wanted by OP.
I think OP is not even under on all those tiers. Just a gambler that wants to expect something good out of it. That was a risky decision if OP is just a regular and average gambler and will consider its gambling activity the main source to cover all their household expenses.
Better forget that OP's plan unless he is capable of doing gambling financially without affecting their primary budget.