I record and upload footage from super car meet ups, which has led me to reach over 200,000 total views and 3000+ subscribers on YouTube.
I have started making a few cents from YT ads, but I would like to turn my hobby into a real side income.
Does anyone have suggestions for what kind of content fans will subscribe to my kasu for?
Perhaps you could sell some of your footage as stock footage using the kasu shop feature?
If you really want t do the subscription model you could possibly interview the super car owners, to give your fans the behind the scenes scoop on owning certain cars?
I really like the stock footage idea, I have tons of great unpublished content 
Kasu shop it is!
You will make a lot more money doing this independently on kasu compared to stock footage platforms, the royalties they pay are literally a few cents per use!