What is the purpose for God giving people dreams and visions of events?

It seems the purpose is to respond to dreams or visions that we have, and not to simply wait to see if it will happen.

How would a person respond to a dream or a vision?

A powerful way to respond is by prayer. Prayer for those that were seen in the dream or vision, for protection and deliverance, that they would turn to God and give their life to Him (Acts 2:38), for repentance. God can change events. God responds to repentance.

The people of Nineveh were destined for destruction. (Jonah 1:2) Just as God speaks to people today with dreams and visions, God spoke to Jonah. Jonah responded, finally, (Jonah 3:1-3) and went as God told him and preached to those in the city of Nineveh of the impending doom. (Jonah 3:4) Because the people of Nineveh repented, the course of events was changed. (Jonah 3:5) God had mercy on them and did not destroy the city. (Jonah 3:10)

Jonah had an obligation to God to respond. This is why God spoke to Jonah. God was going to destroy Nineveh. Jonah responded as God wanted him to, and Nineveh was not destroyed.

Today when we are given visions or dreams, God wants us to respond. We are able to intercede through prayer, even travailing intercessory prayer for those that we saw in the vision in harm’s way. People can be effected by prayer to make a change of mind, repenting of the direction their life was going, and events can be turned.

There are many dreams and visions that never come to pass because of a response to the dream with travailing, intercessory prayer. It is through faith in those dreams and visions that they are from God that leads us to prayer.

We do not need the so-called ‘reward’ of seeing these dreams and visions coming to pass just so we can tell people that we have heard from God. Rather, God wants a response from us so that the impending doom of the vision does not come to pass.

It takes faith to respond to dreams and visions and faith to believe that God answered our prayer and changed the event. This is our reward, just us knowing that God used us for good in people's lives when we respond to a dream or vision with heartfelt prayer.