What is the point of praying to God for something that you want? and some people don't pray and they get ?

if God knows everything.. before you want and I heard some people get what they want without praying in this life. they are non-religious or believe in God.. but some people who are poor or don't have good luck in their lives.. they pray God with devotion but I don't see God won't change their lives for a life of prosperity or getting better things? how can I explain those things?