Do I have the right to be upset??

So I have a vintage Polaroid right. I love taking pictures with it. I FINALLY found film after 7months if looking. Now mind you the film isn’t cheap. It’s roughly $70 for a pack of 30 . I took a picture of my niece of brother today. I specifically told him I wanted to keep it. And not to take it home. I set it to develop I came back a few minutes later to check on it. And it’s gone. I thought it fell so I looked for it. I look outside and my brother has it in the car as they’re driving away. Like I get he wanted the picture and that’s his child. But they can print off pictures through their phones. I can’t get the same “aesthetic” feel. Maybe I’m being a bitch or selfish idk. The pictures are my thing and everyone in my family knows it. They know how much that stupid camera means. And especially that when I take a picture it’s mine and it’s going in my book. I’m not even sure I have a right to be upset. Because like I understand he wanted it. I was going to send him a picture after it developed. But like I didn’t even get to see how it turned out before he took it. Idk, it’s stupid little things like this that make me really upset.