Is AUTHOR wrong in the post ? POST : so this happened a while ago and I'm curious if I was the asshole.

It was just before my 20th birthday and I decided I wanted to see a movie as my birthday party/gift to myself, I discovered that How to Train Your Dragon 3 was out so I thought id go see it. 

I posted on the group chat the date and time of the movie and asked if anybody wanted to join me for a birthday movie. I said its completely optional if you want to join me. 

most of the group agreed and I was happy. 
That was until one of them said why don't we pick a different movie, I replied saying that it was my birthday and it's the movie I picked, we could see another movie on another day if you want, but I really want to see How to Train Your Dragon. 

After realising they wouldn't change my mind they told me they weren't coming and stopped talking in the group chat. 

I'm now unsure if I should have changed the movie or not.

AITA?

and just incase anyone asks, I like how to train your dragon because it's a good movie. 