Now i am pretty much completely new to trading. My question is. When, lets say Apple, comes out with a new iPhone. How come poeple dont buy large amounts of Apple stock before, and then sell a few days after the release of the iPhone. Iphones sell out every where and its pretty much a gaurenteed profit right?

Now there may be something that I'm not understanding as to why people dont do this, im not sure. Just always wanted to ask. Thank you