FILE UPLOAD FOLDER PERMISSION 777

[eluser]Unknown[/eluser]
In CI user guide there is such line:

You'll need a destination folder for your uploaded images. Create a folder at the root of your CodeIgniter installation called uploads and set its file permissions to 777.

How secure is it when I am developing real web application? For example: social network and I want to upload user's profile pictures. I think I will have privacy problems when user's will want to upload private pictures.