So my (21F) brother (16M) wanted this expensive Nike Elite Hoops backpack for school. Our parents were hesitant because of the price, so he asked me for it. It was above my budget, but I agreed on one condition: that he stop calling our parents “stupid/dumb” or using derogatory terms with them. (just to note, the condition didn’t apply to me since siblings call each other names all the time, and I honestly don’t care) For context, my brother has a habit of acting superior, emotionally blackmailing my parents over money (“you don’t care about my future if you won’t pay for X”), and constantly putting others down. We’ve explained that it’s about respect, but he insists calling them stupid is just 'a fact' if they are actually stupid. Fast forward to yesterday. We were joking around something and I teased him by saying that "everything that he says is stupid". My parents laughed, and he immediately argued that it’s 'unfair' they laugh when I say it but get upset when he says it to them (mind you, he called me stupid multiple times before I said it during our discussion). Things then escalated into one of his usual bet where my dad reiterated something he has said before, “If you get into a top 10 school, I’ll take out a loan to send you and even buy you a Lamborghini.” My brother immediately said, “Okay, if I get into a top 3 school, you give me all your money and be homeless.” My mom was furious at him, but that’s how he always talks. Eventually he called all of us stupid again. I reminded him that his backpack was conditional on not doing that, but he just said "I don't care" and called them stupid again so I took it away. In response, he said "I don't care" again and started playing games/talking to his friends. This morning he’s sulking, saying “do you know how crazy it sounds that you took away my backpack, something I’ve wanted for so long, just over this?". He says I’m overreacting, especially since he has an exam and wants to use it. But to me, the deal was clear, and I even recorded him agreeing since he has a habit of backing out of bets when it doesn’t go his way. On one hand, I know I probably shouldn’t have joked about him saying stupid stuff in front of my parents. But to me, there’s a difference between a one-off sibling joke and him constantly disrespecting our parents. On the other hand, he wanted the bag to fit in at school (his classmates are pretty wealthy), and I do feel bad about taking it away before his exam. So…AITA for sticking to the deal and not giving it back?