Find where your dropbox executable is using the following command:

which dropbox

This will show you the actual filepath of the dropbox executable file. In most cases, it will be /usr/bin/dropbox. Open it with your preferred editor:

sudo vi /usr/bin/dropbox

Find the following line and change

PARENT_DIR = os.path.expanduser("/var/lib/dropbox")

to

PARENT_DIR = os.path.expanduser("~") 

This will direct Dropbox to access your Home folder for the config files. Save and restart dropbox:

dropbox start -i

Further explanations