It doesn't have to do with Amazon. It is just how ads work.
Of course when you buy a product that is heavily advertised you know that you are paying for it, Amazon or not. That's why, when I see an ad campaign for a product I may want, it is a signal for me to look elsewhere. Some competitor may use what would be ad budget towards offering lower prices or better quality.
As for Amazon, it is not cheap! It is convenient, fast delivery, easy returns and all that. But if you forego that convenience, there is usually a cheaper option: local shops, Chinese platforms, direct sales, etc...
Of course when you buy a product that is heavily advertised you know that you are paying for it, Amazon or not. That's why, when I see an ad campaign for a product I may want, it is a signal for me to look elsewhere. Some competitor may use what would be ad budget towards offering lower prices or better quality.
As for Amazon, it is not cheap! It is convenient, fast delivery, easy returns and all that. But if you forego that convenience, there is usually a cheaper option: local shops, Chinese platforms, direct sales, etc...