My code does not disappear when people take and modify it, is's still mine, published in my repositories and saved somewhere in my backups. It's an honor when people fork and modify it. One of my old projects on GitHub has new forks every now and then. I randomly look into them and cherry-pick their changes if I feel like it. ;-) Of course, as my repository is the official one, the chance to drive away traffic from me is rather small.