[greenyoda]

"you will eventually be thrown away as an unhappy and unenthusiastic employee and be given a bad review, no matter what your achievements or sacrifices were."

This is a very important point. The company's founders have absolutely no loyalty to him - they'd throw him out like trash (without the slightest regrets) as soon as it becomes convenient for them. Thus, he should not have any more loyalty to them than they have to him, and should not feel guilty about leaving to pursue better opportunities.