THE GREKS WERE PEOPLE-HATERS
They came to Earth in their space ship, bearing fabulous gifts - such as machines that did any day job automatically, and fertilizer that made plants shoot up overnight. But they presented their gifts with contempt, and with a look in their eyes that made people feel "creepy".
Still, because of the brave new world they promised, they Greks could be forgiven anything - until they left and people discovered the machines were breaking down. Then their only choice was to beg the Greks to come back, on their own terms. And they knew the terms would be hard...