Is this a problem or am I overreacting?

I have a little brother who I love dearly we have a large age difference so it’s always been harder for us to get along.

We’ll ever since he was around three he’s always acted a bit differently. He’s the only boy and the youngest child of our family. I’ve noticed my mom always babies him for example, at age seven he still goes to the bathroom and isn’t able to wipe or clean himself. He is able to he just won’t because he doesn’t feel like it. He’s also completely addicted to technology he’s never not using technology when he’s on the bathroom, when he’s eating, the only time he’s not is during the school day. That probably contributes to it to.

The thing that worries me the most are his anger problems. A couple days ago we were playing with this furniture for fun and that we were going to have to move in a couple minutes. When I said I’ have to move he said no. I said we can’t have it out here in the middle of the hallways sorry buddy. And he started yelling and crying. I said dude it’s not a big deal we can play with something else and he started yelling I hate you over and over at me and throwing all his toys at me which was actually really painful. He does this every other day. He always yells and threatens people when they don’t get him what he wants. I remember once he threatened our mother for not getting him the right food. And he’s really intelligent for his age he’s amazing at reading, writing, and math. And he has some moments where he’s really sweet and others where he really frightens me with his threats and anger. My mother and father usually just let it go and get upset with me when I think what he’s doing is wrong.

What do you think is up with him? And what should I do? Is this how usual seven years olds act?