Why sittest thou thyself alone? — The emphatic word is “alone.” Why dost thou not, Jethro means, devolve a part of the duty upon others?
Related Commentaries of Exodus 18:14
Exodus 18:14
14 And when Moses' father in law saw all that he did to the people, he said, What is this thing that thou doest to the people? why sittest thou thyself alone, and all the people stand by thee from morning unto even?