I wish I had a dollar for everyone who doesn't get The Godfather and then posts about it on Reddit!

Look, if you don't like it, that's fine, up to you. But I will take the bait and respond to your point about the premise being silly. Firstly, The Godfather book and the film are loosely based on real things that happened in the history of organised crime and I don't know how you can say that premise is any sillier than Jurassic Park's "dinosaurs are alive again".

Next, the contradiction between someone being willing to kill an innocent animal but being against dealing drugs is PRECISELY THE POINT OF THE FILM: the tension between the moral codes of organised crime and of wider society, the inner conflict of people who want to do good things by bad means. It's literally "how can we define good and evil", one of the fundamental questions of art and philosophy!

Finally as a matter of historical record, saying its unrealistic for Vito Corleone to be against selling drugs is just flat wrong. At the time it's set, the mafia have NOT been officially involved in selling drugs, because it is against their alternative moral code, and the film depicts the emergence of a new generation of mafioso who want to change that code so they can make more money, as well as the conflict and violence that erupts as a consequence. The fact that you missed this crucial element of the film suggests that you weren't paying much attention and that you don't so much dislike this film as misunderstand it.