THIS! Dealerships have little qualms about a customer buying a vehicle from another dealership. They do LOVE it when a customer who bought a vehicle elsewhere makes their dealership their service center. I've done it multiple times over the years. There's a reason why that is so. Like you said, it's where the big money is. Plus, great service can mean that a future sale will be made through that dealership. The customer spends much more time over a multi-year period at the dealership service center than in the showroom.
Yeah.
Sales equates to about 2-4% (even with the crazy sale prices last year) of net income, while service comes in around 45-50%.