HoH problem representing a data structure.

I'm trying to fully understand references so I created a data structure to
stores the output of users on my system who share home dirs.
I use a HoH to represent this data set but its not working as expected.
Conceptually I can visualize how the data should look but I cant get the
output any assistance will be appreciated thanks.

#!/usr/bin/perl -w
use strict;
use warnings;
use Data::Dumper;
my $file = '/etc/passwd';
my $hash;
my ($user, $homeDir);
my $count=0;
open(my $fh, "<", $file) or die("Fatal error unable to read $file: $!");
while(<$fh>) {
  next if /^#/;
  ($user, $homeDir) = (split /:/,$_)[0,5];
  $hash->{$homeDir} = $user;
}
print Dumper($hash);

My output looks like the following:

$VAR1 = {
          '/var/imap' => '_cyrus',
          '/var/empty' => '_unknown',
          '/Library/WebServer' => '_www',
          '/var/xgrid/agent' => '_xgridagent',
          '/var/virusmails' => '_amavisd',
          '/var/spool/cups' => '_lp',
          '/var/pcast/agent' => '_pcastagent',
          '/var/root' => 'daemon',
          '/var/spool/postfix' => '_postfix',
          '/var/teamsserver' => '_teamsserver',
          '/var/pcast/server' => '_pcastserver',
          '/var/xgrid/controller' => '_xgridcontroller',
          '/var/spool/uucp' => '_uucp'
        };


If I replace line 13 with the following the data structure looks some what
like what I wanted but it still not correct.
$hash->{$homeDir}->{$user} = 0; basically the value 0.

$VAR1 = {
          '/var/imap' => {
                           '_cyrus' => 0
                         },
          '/var/empty' => {
                            '_spotlight' => 0,
                            '_appserver' => 0,
                            '_ard' => 0,
                            '_appowner' => 0,
                            '_mcxalr' => 0,
                            'nobody' => 0,
                            '_qtss' => 0,
                            '_securityagent' => 0,
...
...
...

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