Python could not import the module virtualenvwrapper.hook_loader?

you need to change VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3 to VIRTUALENVWRAPPER_PYTHON=/usr/local/bin/python3 for MacOS

You have to install virtualenvwrapper separately for different versions of Python:

pip install virtualenvwrapper
pip3 install virtualenvwrapper

The first one is for Python 2.7, the second for Python 3.

Installing virtualenv by both, pip and pip3 doesn't make any sense because installing it by any one shows virutalenvwrapper in both, pip list and pip3 list.

The right way is to copy the following code in your ~/.bashrc.

VIRTUALENVWRAPPER_PYTHON=$(which python3)

NOTE: Use the python version you want to use, in my case it's python3.