A few habitats and guest shops makes the profit from guests steady enough to not need the exhibit breeding profits. I have three habitats and im sitting on more cash than i can spend, selling exhibit animals for cash just isn't worth it by that point. I say stuff some contraceptives down the frogs and get to the fun part instead
If you use contraceptives then you're still having to manage animals later on on a massive scale as you have to then purchase the new animals after your contraceptives one die off of old age.
So either way, you're in a never ending loop of micro managing animals instead of building your park. You're either micromanaging breeding or you're micromanaging refilling your habitats and exhibits.
I don't want to play "Planet Caretaker" I want to play Planet Zoo. This animal micromanagement is something my workers should be doing. It's absolutely bonkers and it gets exponentially worse as your zoo gets bigger.