I play regularly at Betfury, but I think the probability of winning is equal to that of all casinos, if you play a lot you may have a winning streak, but it is always very easy to lose, however when they are referred I have no experience in it, To have so many referrals I imagine you must be a YouTuber or influencer, it is a good profit and I congratulate you. In my case I only bet with the coins, sometimes with BFG but it is a great risk, however I think that is what makes this exciting.
It all depends on luck, nothing more. The one thing that is different on Betfury is that their house edge is higher than other sites (2 % vs 1%), so in the long end you will probably loose more money on Betfury but in the same time you also win BFG tokens given you daily dividends.
You are right, when you are playing and betting with your coins for what you lose you get a little more BFG, and seeing it differently you generate more staking, of course you do not want to lose in the short term because for some players they can suffer from disappointments that do not want to play more, it all depends on how much you are willing to lose, that is where the type of psychology and control of the player comes in that for everyone is not so easy, sometimes playing many times one believes that it is invincible and the profits increase, there is where you have to be in control, you can be on a winning streak but in a moment or in a short time you can lose.
I don't bet on BFGs for the same reason, I take great care of them for the amount of bets, some burn their BFGs to get Satoshis, but that depends on what each player is looking for.