With the referral program, yes someone can earn big money if he/she can get whales as his/her referral.
I'm pretty sure there some people who earn decent amount of money from referral system, but it is rare to find them share how much they have earned.
There was also other way to earn, where people can invest in casino's bankroll and I've seen some people earn nice profit by investing.
When it comes to gambling yourself, the chance to earn/win big money does exist as long as you are lucky and you can stop at the right time.
Referral earnings are mainly about luck. No point having 10,000 of them if they are "dead".
On the other hand, a high roller lucky to use your refcode could net you thousands within a short period of time. I had a few, but on the wrong website.