A.T. Robertson Commentary Mark 1:17

"And Jesus said unto them, Come ye after me, and I will make you to become fishers of men." — Mark 1:17 (ASV)

Become (γενεσθα). Mark has this word not in Matthew. It would be a slow and long process, but Jesus could and would do it. He would undertake to make fishers of men out of fishermen. Preachers are made out of laymen who are willing to leave their business for service for Christ.