Because the upside of having a powerful recognized brand exceeds the risk. A couple millions people might know about cyberpunk, billions of people will recognize Keanu Reeves. Cyberpunk isn't going to make the news or newspaper without Keanu Reeves or some other big name. Getting people to actually think about the game is a lot of the battle. Ps. Keanu should move back to Canada, rec hockey teams always need a goalie.