Prosperity teachers sometimes teach that if we give, God will in turn give back more to us than we have given. This, then, becomes an incentive to give and a subtle way of advocating the idea that "God wants you to be rich."
There are two main problems with this worth mentioning. First, while it is true that God absolutely does give back to us more than we have given (see, for example, Matthew 19:29 or the feeding of the five thousand), this is not always (or usually) financial. God gives to us in a multitude of ways, and finances are only one such way—and, by far, not the most important.
Second, when God does give back to us, it is not so that we can keep it to ourselves—as though God intends for his further outpouring of grace to terminate on us. Rather, as we are blessed more by God (in all ways—not just financially), he expects us to in turn bless others even more. This doesn’t diminish the significance and meaningfulness of his grace but actually increases it even more, for we experience his grace most fully when it is a means of further serving others.
We see both of these realities in 2 Corinthians 9:10-11: "He who supplies seed to the sower and bread for food will supply and multiply your seed for sowing and increase the harvest of your righteousness. You will be enriched in every way to be generous in every way, which through us will produce thanksgiving to God." We see here that God's blessing is not merely financial because Paul writes that he will enrich us "in every way." And we see that God does this so that we can in turn bless others even more when Paul writes that God does this so that we can “be generous in every way."
But the verse doesn’t even stop there. It reveals to us a third reality as well: It is not simply the case that God’s grace is intended to terminate on others rather than ourselves. It is not ultimately intended to terminate on our neighbor, either. Rather, the ultimate aim is to "produce thanksgiving to God." God's grace, in other words, terminates finally on God, not man. It is from him and ultimately to him. God’s grace is God-centered.
So yes, God does give back to us more than we have given, but this is not always (or mainly) financial. Further, it is intended not to terminate on us, but rather to be a means of enabling us to be of even greater service to others—which ultimately redounds to his praise.
God loves us too much to treat us as cul-de-sacs. It is precisely because he loves that he does not intend the blessing that he gives us to terminate on us.