He flees because he is a hired hand and cares nothing for the sheep.
13. The hireling fleeth. The reason is, because he careth not for the sheep, which means, that his heart is not moved by the scattering of the flock, because he thinks that it does not at all belong to him.
It is not certain whether this discourse was at the feast of dedication in the winter (spoken of Joh 10:22), which may be taken as the date, not only of what follows, but of what goes before (that which countenances this is, that Christ, in his discourse there, carries on the metaphor of the sheep, Joh 10:26, Joh 10:27, whence it seems that that discourse...
Commenting on John 10:1-18
The hireling fleeth, because he is an hireling,.... And has no propriety in the sheep; had he, he would abide by them, and defend them; but because he has not, he will not expose himself to any danger, but leaves them: and careth not for the sheep; what becomes of them, providing only for his own safety.