Christian believers use a lot of terms and expressions foreign to nonbelievers. Even many who attend church regularly don't know the meaning of some of these terms.
A common one is born again. Believers will ask people, "Are you born again?" as if the person would know what they're talking about. Sometimes believers approach a person and tell them, "You need to be born again!" But unless it's explained, the term doesn't mean much to them.
Under the Mosaic Law even when Jesus walked the earth, Jewish men were expected to attend three feasts celebrated at the temple in Jerusalem—the Feasts of Passover (and Unleavened Bread), Pentecost (or Weeks), and Tabernacles (or Booths).
These were important as memorials of God's faithfulness to His people at pivotal points in their history. They were also events that held greater meaning and significance for the future of those who trust in the God of Israel—the Living God.
As with many events and miraculous signs in John's gospel, this event at the end of Chapter 2 was illustrative of the Lord's ministry on earth with eternal impact and significance.
People throughout the world are intrigued by illusions, magic tricks, and sleight-of-hand artists. It's not just because they're clever and entertaining but something inside us wants to see something supernatural.
When Jesus did miracles in the Bible, they weren't illusions or magic nor were they for entertainment. His miracles were bonafide supernatural events with a purpose.