Many people makes very large money from referrals. I have a friend who got upto three referrals that gambles very high and he will be sleeping and decent money will be hitting his account. Was wondering if those people will keep gambling and he keeps smiling without sweats.
You only see the result, finding gamblers who would sign up under your referral is not easy, your friend is lucky he got consistent bettors signed under him. I have some referrals as well in the past, I'm making money although not really that big, but that time bitcoin as still very cheap, if I didn't spend it, I could have earn a lot of money now.
^I don't know in general if a gambling casino industry will give the same percentage of referral from the revenue they will get, as I have known, it was ranging 5% to 10% of the revenue they received. So it is expected that you will receive a small amount because it is rare that there is someone who gambles in a big time, not unless, your friend who signed up under your referral is a billionaire.
However, the profit that you may get in referrals is not bad there are too many of them.