Satan controls major world organisations, governments, groups, religions from the top. Since people follow organisations or governments etc. leaders. Satan only needs a (relatively) few faithful followers to control the world.
Matthew 4:9-10
Again, the devil taketh him up into an exceeding high mountain, and sheweth him all the kingdoms of the world, and the glory of them; And saith unto him, All these things will I give thee, if thou wilt fall down and worship me. Then saith Jesus unto him, Get thee hence, Satan: for it is written, Thou shalt worship the Lord thy God, and him only shalt thou serve.
John 14:30
Hereafter I will not talk much with you: for the prince of this world cometh, and hath nothing in me.
John 18:36
Jesus answered, My kingdom is not of this world: if my kingdom were of this world, then would my servants fight, that I should not be delivered to the Jews: but now is my kingdom not from hence.