What opinion of yours did a complete 180?

Fountain pens are for pretentious jerkwads who want to show off. Turns out, it was just that one pretentious jerkwad with a fountain pen that drove me nuts in high school, and fountain pens themselves are actually really fun, and the online community is one of the nicest I've met. I love these pens!
— MidnightCootie

My concept of weakness. I used to think that crying was weak. Being the first to apologize was weak. That you were strong to hold a grudge. That letting go of anger and forgiving people was weak. That hitting people where it hurts the most is the most satisfying feeling in the world. I was brought up in a really toxic family. I have recently realised how much of a jerk I was.
— TheNameIsPikachu

I used to hate bell peppers. Now I try to incorporate them into every meal, and my husband attempts to prevent me from so doing.
— GoatsWearingPyjamas

'why don't people use the search bar on ask reddit to see if a question has already been answered'. Realised that it's fresh answers most of the time.
— george1984orwell

I was hardcore into new age beliefs and alternative medicine for most of my life. I even started a naturopathy degree. I don’t even know what happened but over the course of a year I realised ‘oh, so this is all bs...’
— sarbot88

Euthanasia. I was very against it. I used to say that you never know, there's always a chance, no matter how tiny it is, that they would find something at the 11th hour to save someone. I remember saying "Imagine you kill someone because they suffer too much, and there's no hope. And 2 weeks later, they find THE cure for that. How would you feel?". Then I got older, and great-grandparents, grandparents and their friends got older too, and I saw what suffering truly means....and yeah now I don't consider that an very unlikely hypothetical chance that a cure might be found is worth it.
— shrekine

'Vaccines aren't good.' To be fair, my dad shoved that crap and a bunch of other shit down my throat my entire adolescence.
— Rednartso

Wanting kids as soon as possible. With 6 Years old I became uncle for the first time (both my sisters are 18+ years older then me) And I babysit alot between my 4 nieces. I even became a kindergarden teacher.... but now I work in a different field and see how shitty my teenage nieces are too my sisters and Im just like 'Ill wait abit longer' Edit: wow. Well this is now my second highest comment ever. So from all the replies i gather that teenagers are just assholes. Now Im wondering if I was like that aswell...
— MotherOfQuaggan

Top 10 Answers