Thomas Edison was "stupid." People told him that you can't invent an electric candle. It just can't be done. But Edison was clearly too stupid to realize the truth of what they were saying, because after a thousand failed attempts, Edison finally succeeded, changing the entire world with his invention of the lightbulb.
Likewise, many people believe that prayer is a waste of time. And if you are generous, you will be taken advantage of. Therefore prayer and generosity are stupid. And yet in His Sermon on the Mount, Jesus tells us to be stupid in both prayer and generosity, to keep going with both, even when those around us think we are being "stupid."
Because there is something to be said about stupidity.