“Made a fool of.” From empaizō (#1702 ἐμπαίζω), “To trick someone so as to make a fool of the person” (BDAG, cp Lenski). It was more than just being “tricked” by the magi. Herod reigned by fear and control, so having someone disobey a direct command, from his perspective, was to make a mockery of his reign. He would have expected the magi back the next day, two at the most. He felt they made a fool of him by slipping away, and was furious.
“he killed all the male children…in Bethlehem and all its surrounding region, from two years old and under.” Killing potential rivals was standard operating procedure for Herod. King Herod the Great was so afraid of anyone taking his throne that he even had one of his wives and three of his sons executed because he was suspicious of them. The Bible does not say how many children in Bethlehem were killed, and it is very likely that because the killing was in Bethlehem “and all its surrounding region” that no one kept count. However, the “surrounding region” could not have been very large—perhaps only a few miles—because Zechariah and Elizabeth lived in the hill country of Judah and there is no evidence that John, who was only six months older than Jesus was in danger (although he could have been older than two by the time the magi arrived, likely 18 months to 2 years after Jesus was born). In any case, demographic studies of the city of Bethlehem and the surrounding region done by scholars has led to the conclusion that almost certainly less than two dozen children were murdered, and perhaps only half that many. Although this was certainly a tragedy, Herod’s reign was so filled with violent acts including murder and death that this particular killing is not even noticed in any secular writing of the time or in Josephus. The palace-fortress of Herodium was just east of Bethlehem and was clearly visible from there, and it is likely that soldiers were dispatched from the Herodium to kill the babies.
The fact that Herod’s murder of the children is not mentioned in secular writings of the time has caused some historians to say the record is a myth and that it never really happened. Many of them say it was just an invention by Matthew to build a parallel story of Pharaoh’s killing of the male babies in Egypt (Exod. 1:15-22) into the biblical account of the birth of Jesus. However, that argument is pure speculation; there is no good reason to reject what Matthew wrote.
Many things in the Bible are not recorded in secular history, and Herod’s known character fits with him killing anyone he thought was a rival. Josephus does not mention the killing, but there could be many reasons for that, including that the details of the event were not well known. Furthermore, although there are a few parallels—a very few—between Herod and Pharaoh, there is also such a large number of differences that the average reader never even sees any parallel between Pharaoh and Herod. If Matthew concocted the story of Herod killing the children around Bethlehem to draw a parallel to the story of Pharaoh ordering the death of the male babies of Israel, it seems he would have made the parallels easier to see. Furthermore, if Matthew invented the story of the killing of the babies, it would have defeated his purpose of writing an account of the life of Jesus that was designed to get people to know about Jesus and accept him as Messiah. When Matthew wrote it could still be confirmed or rejected that Herod killed the babies; some of the siblings and most likely even some of the parents of those babies would still have been alive. If word got around that Matthew fabricated what is certainly a major event in his gospel record, then many people would doubt the entire account Matthew had written. But, on the other hand, if what Matthew wrote could be confirmed by people who lived through the events that Matthew recorded in his gospel, then what Matthew wrote would indeed get people to believe, which is exactly what has happened through the millennia; people read the Gospel of Matthew and believe that Jesus is the Messiah and that he died for their sins.
[For more on Herod’s character and ruthless ways, see commentary on Matt. 2:3, “deeply disturbed”].