What is the secret behind the popularity of the game Flappy Bird?

Aka what the hell makes Flappy Bird so popular despite its being stereotyped and a rip-off of many games in every aspect?

Or why the hell does something like this happen?

I just can’t understand. I played that game once and it was so annoying that I deleted it right after downloading. You have heard about Flappy Bird right? Can you tell me the answer?