Why they need people?

The question about aliens is actually the matter of argument. There are people who believe in them and there are people who don’t. Though, in case there are other living creatures in the universe indeed than who are those? And people also say that those creatures are of the higher level of development than we are. And if there are such creatures in the universe and they are high developed generation and they have all those technical miracles and they can hide from us than why would these creatures need people? In case there are aliens that take people away and conduct their researches on people than why would they need so much people for their researches? It didn’t seem too smart in case they have made hundreds of researches and haven’t learned people yet. Why would those smart and greatly developed creatures need people and why would they visit us for thousands time? I guess even in case there are other forms of living creatures in the universe they don’t need us and even if they do it is nit for researches I guess…for food maybe?