You could argue that atheists seem to be more successful because they rely on action rather than prayer to get what they want. But there are plenty of religious people who do just fine. I’m not successful in the eyes of most people around me. I drive second hand vehicles. My business has taken seven years to get to a point where I have to pay the tax man. It’s been 5years since I last had a two week holiday, and I am worried I won’t earn enough to enjoy those two weeks. 
However, because I live where I do, I’m much better off than at least two thirds of the rest of the world. I not only eat, but I eat stuff that has no nutritional value. I throw away food (although I try not to). I have 24/7 entertainment. 
And a great many theists have this too.
The thing I’m trying to get at, is this: one’s success is subject to certain points of view. It’s not wrong to aspire to a better life, but we (those of us with enough to eat) should also accept we are doing well, regardless of our religious orientation. We were lucky to born where were and have the opportunities we have. The successful atheist will have his success to measure his happiness. The theist, rich or poor, always has the failsafe knowledge of the encompassing love of their god. Right or wrong, the power of that belief depending on how strong it is can make up for a lot. Which is probably why the poor cling on to belief that much harder.