Seriously, though. I can't believe I'm actually posting this, but...:
Reasons to be closed source:
- Prevent upstarts from taking your code, modifying it, and redistributing it with malware inside.
- Prevent the game owners from reading your code, finding a telltale heuristic (a.k.a. 'signature' move) that your bot will do every time something occurs, and bot nuking all your users.
- Prevent people from downloading your source, fucking something up, and getting themselves banned.
- Prevent competitors from stealing your source, adding stuff, and selling it.
- Protect paid script makers. Open source = much harder to secure...imagine that.
- The list goes on...