Perhaps magic is not the correct word. Why would a traveler wear a St. Christopher medallion around their neck? Why wear a brown scapular to escape hell fire damnation? Does saying "Hail Marys" repetitiously have any value? If so, what?
Religious medals are worn for devotional reasons. They are a reminder of our need to maintain a life of prayer — including prayer to the saints for their intercession, which as you know is NOT worship of saints. Moreover, there is the real trust in blessed objects as a sort of demon repellent. Now, people who don’t believe in demons will scoff, but I assume you do and understand why a Christian would want to drive them away. Sacred objects and truly holy persons are noisome to demons; they can’t bear to be near them. Any exorcist will be glad to confirm this.
As for multiple “Hail Marys”. Half of the prayer is literal verses from Holy Scripture. Do you read the Bible once in your life and then put it away forever? Is it not good to return to and to meditate on the inspired word of God? The second half of the prayer is a request that the Mother of God pray for us. She was given to John as his mother at the foot of the Cross, and because we’re members of the Body of Christ, she is our mother too. Asking your mother for prayer is the most natural thing in the world, isn’t it? Even more than once?
Why does it matter to you what other people believe?
Are you really that insecure?