Hmmmm I guess I have no idea why monks exist. Seems like a very strange concept to me.
It’s kinda like a fraternity that devotes itself to God.
They exist to pray without ceasing, as St. Paul told us to do. One can pray without ceasing while working in the world and being married (by internalizing prayer, using the “Jesus” prayer, “practicing the presence of Christ.” But one can also pray without ceasing by creating a committed community that prays a daily cycle of prayers and liturgy.
It went on in Jesus’ day in the temple. The Apostles attended those daily prayers according to the book of Acts. It’s ancient and it’s biblical. The roots of it go back to the “Schools of the Prophets” that gathered around Elijah and Elisha and others in the Old Testament.
It’s just plain common sense. If you love God, you want to pray as much as you can. Most people are busy with family but they’ll pray as much as they can. If you give up family to join a community or choose not to remarried after being widowed, you can pray more constantly. Both ways of praying as much as one can are good.
But different. And ancient. And New Testament. (Did I mention the committed virgins and the enrolled widows that St. Paul speaks of???? Monastic communities go back to the very earliest days of the Church.)
Oddly, the Christian groups who proclaim that “we are true New Testament Christians” rarely are so New Testament that they maintain the enrolled widows and virgins as praying communities as described in the New Testament. It’s just one example of people thinking they are going back to the original “pure” or “primitive” Christianity and avoiding all the “human traditions added later by apostate Christians, i.e., Catholics” but who are very selective in which NT practices they “restore.”
Meanwhile, Orthodox and Catholics have had monks, nuns, communities of professional prayers that grow out of the New Testament enrolled virgins and widows all along.
So they don’t need to restore NT practices. They’ve been doing them all along.