How do i convince my brother privacy is important?

My brother seems to not care about his online privacy. He registers to services too easily without pondering, he’s not outraged we need a fucking account to use a vacuum cleaner, it seems he doesn’t care about all the potential risks of having videos of our indoors saved in a cloud. I don’t have strong arguments to convince him that privacy matters other than “if someone gets that, you could be in trouble” and “it’s like having someone watching you h24” and so on. How can i persuade him?