You could use count_many_users_posts()
.
$args = array(
'exclude' => array( 4, ),
'fields' => 'ID',
);
$users = get_users( $args );
$user_posts = count_many_users_posts( $users );
foreach( $user_posts as $user => $posts ) {
if( $posts < 3 ) {
unset( $user_posts[$user] );
}
}
$user_ids = array_keys( $user_posts );
shuffle( $user_ids );
for( $i = 0; $i <=4; $i++ ) {
$user = get_userdata( $user_ids[$i] );
// display your user info here
}