> I got more cars coming, see you on Monday!

This is sort of the problem, though, isn't it? There aren't more cars coming on Monday.

Have you run out of money?

your assumption is that by buying everything I got from me and selling at an higher price than me (doesn't mean higher markup) you are pushing me out of business.

Or that you are monopolizing the market buying all the cars, assuming that you can buy the tens of millions of used cars around.

You're also assuming that I am stupid and I'll let you do that, in the name of principles.

The second time I see you coming in to buy a car I'll check who you are, the third time you come you'll be greeted by a "we are not a B2B company, find another supplier".

The point is dealerships have a limited number of cars to sell, and it's unclear when the next ones will come in. If I want a car and the dealership is out, I'm fine paying a premium or financing the car through them or whatever to get priority. That's how the market moves up.

Aside from the last sentence, I agree, and a fun reminder that raising prices is a good way to mitigate against high demand / low supply.

That said, I was expecting to be countered on the inherent riskiness of my position, as I'd forgotten that it is indeed mutually beneficial but for that.