I want to vent about why I hate weddings to my friends
What about weddings makes you hate them?
They take a long time to plan and it is so much work.
If that's how you feel, no problem!  There's nothing inherently wrong with having a strong opinion on something.  Just don't expect everyone to share it!
I just don't understand you people who think that weddings are fun. It's super stressful!
There is nothing wrong with thinking that. Weddings are not for everyone and you do not have to like them.