Even if you buy the car in cash, the purchase is one time payment, but after that they have you as a recurring customer for the long run with service costs which is where the money comes in.
No wonder modern cars are designed to be as difficult to service as possible by the owner. In my older Fiat I could change the air and cabin filter without any tools in 2 minutes. On my latest one they're both bolted with custom screws. WHY?! On my older one the user manual would be full of instructions on how to perform small maintenance tasks yourself. On the new one all it says is contact your authorized dealer. It's as if the cars of the past were designed by engineers and cars of today are designed by MBAs to be disposable black boxes like laptops or phones where only the genius bar employees have repair access.
The whole auto industry today is a large scale scam where we trade the environment and our health for corporate profits and is being marketed to us as a desirable lifestyle we should all aspire to which I wish not take part of but I can't due to shitty public transport in my city and employers placing their offices in buttfuck middle of nowhere to save on rent.
Unfortunately, the auto industry comprised of manufacturers and dealers have too much power in some European countries, and, as they keep touting how our dependency on car ownership is creating more jobs, their influence on the future of urban planning ain't going nowhere.