having your own betting site will force OP to have to invest a lot of money, just to have the site itself, something unique and original made just for OP has a very high price, then you have to hire a team, which is also money because they are people who need to receive a salary and it is not a meager salary that they accept, then they have to have a license, according to what I read once and if I am not wrong the license is something that they also charge money for any casino to have, so that it means that OP would also have to pay to have a license.
A good affiliate has their own network, they spend a lot of money to bring targeted traffic. To reach the traffic they spend a lot of money, and the site owners basically received this traffic almost for free. If there is any conversion, then they only pay otherwise their cost is zero.
Yes, there are other factors which a owner needs to worry, technical aspects, accounting, customer management, website maintenance, the Bankroll adds too.
From the description of OP, I feel he is master in bringing traffic. Someone like him can partner with someone who has ability to look after the rest instead of being just an affiliate.
Basically, being an affiliate means having a passive income, because once you've got the referrals directed to a platform and they started using that platform under you, what you earn after that is all passive income since you won't be doing anything at all, but what you are suggesting is not that simple and requires a lot of constant work, if you are partnering up with someone for running a platform, you will need to bring traffic constantly and one-time isn't enough.
So he might not be up for the task if you suggest them to partner up with a casino or someone to create a casino since he is good with bringing targeted traffic, what he basically does is direct his network towards a platform and then earn passive income, I'm not really sure if he works constantly on bringing new referrals or not.