I absolutely disagree with this.
If you are able to have savings after all living necessities, you can be using not more than 1% of your income on gambling. No need to think about the budgeting like it is something special.
I spend more on things that add up to me than things that do not add up.
You might be missing somethings from what the Op meant.
From my understanding, he was driving to what categories between responsible and irresponsible gamblers. As learned gamblers just as you said, gambling budgets should be treated optional since it's just fun activities while basic human needs and investment plans should be made a priority and comes first.
That defines you a responsible gambler because if you've to loose those certain amount of gambling, you'll have nothing to regret about.
While there're also those irresponsible gamblers who considers gambling first once they've money and they usually regrets it after loosing. So they either struggles on affording those necessary needs neither do they see improvement in their incomes.