Running the 1.7.3 installer on OS X Yosemite 10.10.4, I get the following error when I try to run vagrant.
Of note, the /Applications/Vagrant directory is not created, but it is installed into /opt/vagrant. The binary is also not added to the path.
The home directory you specified is not accessible. The home
directory that Vagrant uses must be both readable and writable.
You specified: /opt/vagrant