User Profile and display_name

I never could figure this out. User "display name" can not be updated via user profile?

By the way in case it helps anyone, here's what I ended up doing:

• custom text field named display_name in user profile
• for user profile, a field group with ID user-profile
• the following code to update user info after saving the MB profile

add_action( 'rwmb_profile_after_process', function( $config, $user_id ) {
    if ( $config['id'] == 'user-profile' ) {
        if ( $uname = $_POST['display_name'] ) {
            $args = array(
                'ID' => $user_id,
                'display_name' => $uname
            );
            $update = wp_update_user($args);
        }
    }
}, 10, 2 );

• and this to update the default profile field value in case it was changed elsewhere (ie. Edit account page)

add_filter( 'rwmb_display_name_field_meta', function( $meta, $field, $saved ) {
    $current_user = wp_get_current_user();
    return $current_user->display_name;
}, 10, 3 );