Actually, the funds are used to run the church, and to pay for costs and expenses. It also pays for the ministers salary. The Bible does give a pretty clear description of how the money is to be used.
If you were to think of sitting inside a hot church on a very hot summer day, rather than an air conditioned building, then you would not have to wonder about the light bill, and what it cost to keep that building cooled off, so that the members, can sit in comfort.
There are lots of costs associated with buildings, upkeep, maintenance, lawns, and the utility bills, etc. that are not being added in. Just take some time to add up the overall costs, and you won't need to wonder, you will know.