Here is the verse that explains clearly why ministers always ask for offerings, tithes and donations. Many a times they fail to get this message across simply due to wrong word choice.
10 "Bring the whole tithe into the storehouse, that there may be food in my house. Test me in this,” says the LORD Almighty, “and see if I will not throw open the floodgates of heaven and pour out so much blessing that there will not be room enough to store it."
If we benefit from any ministry we should help them stay afloat by contributing to their daily upkeep so they can continue to help us and others. That is only fair. It is not how much one contributes but the thought of supporting God's work that is important.
May we all find blessings in this word of God. Amen.
To God be the glory and honour through Jesus Christ our Lord. Amen.