Agreed. I probably shouldn't have allowed referral/affiliate work into the final list.. it is *not* gambling/betting as you say. It is business.
Yes referral links isn't really a gambling though it's coming from the casino but it's not. No money capital/bankroll is associated with for the referror to gamble but the referral has to gamble.
I do believe that some people can be successful in sports betting but it requires a lot of knowledge and research. Additionally you need a large bankroll to counter any unlucky streaks.
It's the easiest for me, not dice, not slots and other games. Sports betting for me is the easiest if you know the sports, the teams and the news and current events for that specific sports that you are betting.