Big difference between stupid and foolish. In Galatians 3 the Complete Jewish Bible calls the people “stupid”.
1 You stupid Galatians! Who has put you under a spell? Before your very eyes Yeshua the Messiah was clearly portrayed as having been put to death as a criminal! 2 I want to know from you just this one thing: did you receive the Spirit by legalistic observance of Torah commands or by trusting in what you heard and being faithful to it? 3 Are you that stupid? Having begun with the Spirit’s power, do you think you can reach the goal under your own power?