Too much advertisement?

The other day I went to McDonalds and while I was eating my meal on the tray I noticed an advertisement in the middle of it. They are advertising in their own fast food restaurant, I mean come on we already bought food from there, it does not mean we are about to buy some more just because we saw the advertisement on the tray and something hanging from the ceiling. I understand commericals but even after someone buys their food they still want us to buy more, the society we live in has become way too selfish, don't you think? One buys the food, eats it, and then they see another advertisement to buy more? I noticed a girl with her family and as they were leaving she happened to see the sign dangling from the ceiling that advertised an Iced Coffee so she begged her mom to buy her one. Meaning, this type of advertising works. I believe society depends too much upon advertising and advertises way too much than what they're supposed to, am I right?