You shouldn't profit off the ignorance of someone else.
Mike is trying to buy a car, and the seller has never sold one before.
Mike wants to make an offer for the car.
Mike gives the seller a fair price.
Mike lowballs the seller by $1,500 below the car's worth.
The seller accepts it and has extra money that he needs.
The seller accepts the offer and doesn't get what he deserves from the car.