OK, where does it say "three gifts"? It only mentions some substances. It there were 18 wise men and each brought 5 gifts, that would make 90 gifts. Now that is what I call a Christmas!
It doesn’t say the words “three gifts.” The second chapter of Matthew states, “Then Herod secretly called for the wise men and learned from them the exact time when the star had appeared. Then he sent them to Bethlehem, saying, ‘Go and search diligently for the child; and when you have found him, bring me word so that I may also go and pay him homage.’ When they had heard the king, they set out; and there, ahead of them, went the star that they had seen at its rising, until it stopped over the place where the child was. When they saw that the star had stopped, they were overwhelmed with joy. On entering the house, they saw the child with Mary his mother; and they knelt down and paid him homage. Then, opening their treasure chests, they offered him gifts of gold, frankincense, and myrrh. “ You’re correct. Each of the 15-18 wise men might have given one container of gold, frankincense, or myrrh. If that happened, Jesus would have received 15-18 gifts.