My parents always had this rule whenever i wanted something. They said “if you still want it when [birthday/christmas/easter] comes then we will consider it. Usually my interest faded and we avoided a wasteful purchase that i wouldnt have used for very long anyways.

100%. Younger, my spouse and I we were not doing that at all... We had both decent salary and money was not an issue. Nowadays (a few years ago, we both decided to slim down our lives including earning a lot less money) we seldom impulse buy anything. We keep a list of potential purchase and we wait. Quite regularly the 'need' will fade away and when it doesn't, well, it's a good sign it's time to look in it more closely.

I do that for books as well as any other purchase, btw. There is almost never a need to impulse buy a book: we probably all have already many waiting to be read at home. Plus, there are public libraries <3

Too many people are impulse buyers and it seriously pisses me off when i see people throw away stuff they never really used.

They are, but I avoid getting angry at people around me. First, because I remember being like that. Then, because me getting angry won't change a thing beside making me feel bad which I would rather not. Last, because that certainly will not encourage them to change their behavior much either ;)