Missing out on the opportunity to give

In Exodus 36:6, 7 Moses actually told the people to stop their offerings…they had plenty. I’m asking myself, how might this happen in my ministry? I’m also wondering what affect it would have on people if they knew that their “opportunity” to give to a worthy cause, might in fact have a short life span. In other words, if they don’t give immediately, they won’t have an opportunity to give at all to the project (i.e. the tabernacle will be built without their help.)