I've seen a number of people talk about leaving Christianity after God failed to provide for them. I don't know the specific contexts of these people but I have a few thoughts on the provision of God.
God's promise of provision does not include may things that western culture mistakes as necessities. A shiny new phone with high a large data plan and high speed Internet connection is not covered in this provision.
A lot of Christians go through hard times and feel that God has not been true to his word. They have given up many "necessities" and feel that God has in some way "wronged" them.
The reality is a confusion of needs and wants. Western world moves many wants into needs categories.
I see nothing wrong with wanting material things within reason. But we must always see that these wants are not included as part of God's promise of provision.
An example from the bible: Did God provide for his 12 disciples when he sent them out with nothing on them and no money when they went out to preach the word of God. Yes, he did.
Would western culture see these itinerant preachers as being provided for by God? Probably not. The bible is always right even when it seems wrong.