You couldn't be more wrong.
Dealers would love to sell Teslas, but Musk isn't allowing that - sticking to a factory-only model. If you were right, dealers would surely wish to sell Teslas in Texas, where it's illegal to go direct to the consumer, right? They wouldn't be competing directly with the factory there.
Dealers do make money in vehicle sales. Used moreso than new, but they absolutely make money on vehicle sales. The pre-2008 days of $5000 rebates and prices below invoice (and holdback) are no longer. No, it's not a fortune, but they do. And any good dealer will be making another thousand-plus in the finance office after the sale.
Their service department is important, and contributes to a metric known as "fixed absorption" - the percentage of profit the service and parts operation contributes as a portion of the total operating expenses of the dealership. If a dealership operates at 100% fixed absorption, that means their service and parts department completely pay all of the dealership's monthly expenses, and any profit made in new sales, used sales, F&I, or if the dealership has one, the body shop is pure profit.
You really think that a dealership doesn't want a new product to sell, one that will get brand new customers walking through their doors each month? BMWs, for example, already only require one service per year - so the trend towards less service is already occurring.