John Chrysostom

Observe the maliciousness of the man. He was wealthy himself, and to him indeed it was no such great loss; but to them the loss was great, since they were poor, and subsisted on their daily earnings. Nevertheless, these men say nothing, but only he. And observe: "Whom having collected, and the workmen of like occupation," having themselves common cause with him, "he said, Sirs, ye know that by this craft we have our wealth" then he brought the danger home to them, that we are in danger of falling from this our craft into starvation.

Homily on Acts 42 ↗

Theophylact of Ohrid

He drew their attention to the danger: we, he says, are in danger of falling into hunger from our trade. However, what he said could have led them to true worship of God. If, as he says, this man (Paul) is so powerful that there is a danger he might convert everyone, and if from him there is a threat to what belongs to the gods, then one should consider what kind of God his is. Everywhere this Demetrius brings his speech back to the trade.

Commentary on Acts ↗