List users of specific role instead of removing them with specific role

To fetch users from a specific role, you can use the role parameter of the get_users function. Each role has a specific ID; for WordPress’ native roles, these are administrator, editor, author, contributor and subscriber. In your case, you would want to fetch only subscriber users:

$allUsers = get_users( array(
    'orderby' => 'post_count',
    'order' => 'DESC',
    'role' => 'subscriber'
) );