Discouraging brother about internet brides

My brother is making the most stupid decision in his life and I’m not going to stand here while watching him do it. He’s joined this I don’t know group? Club? Site? Something related to dating internet brides. I think he’s only doing this out of spite. He recently broke up with a girlfriend and now he’s already looking for girls to date online? That’s crazy! How do I discourage him from continuing what he’s doing? Are those things even legal??? He’s my big brother and I don’t want to see him fall down because of something like this.