Everything we have came from God. It is all his. We can only give back to him what he has already given to us.
God is providing for us and wants to give us the kingdom—that frees us to give to others knowing that he will continue to provide for us.
The rich fool spared no expense building bigger barns so that he could hoard his possessions. Jesus tells us that a person is not the sum of their possessions. This is good no matter what your status: for the wealthy it means that life has more purpose than just keeping and maintaining THINGS; for the poor it means that life without material possessions can be just as meaningful, fulfilling, and significant as life with possessions.
The widow only had two coins, but she gave it all and for that reason God honored her with a place in scripture. It is not what we have that matters, it is what we do with what we have.
It is not a sin to plan ahead, but to be consumed by our financial planning is idolatry. Jesus tells us we can’t serve both God and money. Either we will use our possessions to serve God, or we’ll try to use God to get more possessions. It comes down to a question of trust. Do we trust God to do what he says he will do, or not? If we trust him, we will have no problem being obedient when he calls us to give.