Answer by Dave C for cron ignores variables defined in ".bashrc" and ".bash_profile"

Because it's not an interactive shell. The same happens when you open some terminals.

Have a look at this question: What is the .bashrc file? | Super User

And also at this one:

What's the difference between .bashrc, .bash_profile, and .environment? | Stack Overflow

Different scripts fire depending on if the connection is a login shell (or not), an interactive shell (or not), or both.

If you want to make bashrc you'll need to make this change:

When Bash is started non-interactively, to run a shell script, for example, it looks for the variable BASH_ENV in the environment, expands its value if it appears there, and uses the expanded value as the name of a file to read and execute. Bash behaves as if the following command were executed:

if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi 

but the value of the PATH variable is not used to search for the file name.

As noted above, if a non-interactive shell is invoked with the --login option, Bash attempts to read and execute commands from the login shell startup files.

Source: Bash Startup Files | Bash Reference Manual | gnu.org