If the rest of the people want to make money steadily, following the lead of the house is never wrong.
In later generations, during sports betting, every city had its own peripheral operations, but in truth, ordinary people were not aware that these operations also had their own backers. Didn't they know that it would be more profitable to go it alone?
They did!
But, it wasn't necessary!
You can't earn all the money, but there's a chance you could lose it all in an instant!
So now, the gang leaders in those cities would rather Donnie reduce his cut than choose to give him up and go it alone!
After all, everyone knew that Donnie was the one truly in control of the outcome of the boxing match.
"A 30% cut is already very little, tell them our cooperation is not just for this one match. If they want to continue making money, they need to accept this rate, or else we'll terminate our partnership with them!"