How to politely tell my boss her company isn't worth my time?

This happened at my job with a coworker, and he felt bad leaving because he learned most of his valuable skills at the previous job, and was leaving to basically compete with the boss who gave him the opportunity to enter into the tree business in the first place.
But he was just honest that it's stressful working for someone else, particularly in a leadership role, and he felt that unless he was getting paid a lot more, he didn't think it was worth it for him to turn down other work he was getting offered.
The boss let him go and do his own thing, turns out there is plenty of room in our local market to fit another tree removal company in, and they are friends on more equal footing now.
If they boss had been a dick about it, he would still have his own gig and all of the boss's other workers would know about it and resent him for it.

/r/antiwork Thread