I have never done media buying for my affiliate websites. All organic SEO traffic.
Cam customers fall in love (or lust) spend... spend... and eventually that burns out. I like the customer that limits himself and is just there for fun ... maybe he spends $100 a month for years ... The more of those you have the better off you will be
Keep getting new customers to replace the ones you lose. The churn rate is around 80% of customer acquisitions (<average>) lost in 2 years.
If you are the website, and have a real 35% to work with, then you can media buy successfully.
What I mean by real is that when one of your customers makes a new account at a cam site you lose him to the site. This has a lot to do with churn rates of affiliate customers too.