Most younger guys I've met who were in training eventually wanted to get back to flying.
You can exclude airline instructors from that because they can go back to the line pretty easy---often at a higher seniority than they started instructing at (so its a pretty good deal---less reserve or whatever and a good schedule/$).
Corporate instructing a different ball of wax. They are limited on time in type and often can't break away for a trip like a contracter can for example. Makes it a little tougher.