First, anyone can change their profession. Secondly, you don't know his job, what was invested, or if it was really a waste. Some jobs truly aren't good fits, whether it be the people, the office, or the system. That doesn't mean they can't get another job that ends up being a much better fit, whether it's in the same industry or not. OP sounds like a great employee to have and was dealing with a boss who didn't get it at all. Not all people do, not all offices are accommodating and helpful. What he experienced was truly shitty, but OP, like all of us have an option.