Thats because, once you have you basic needs covered, a little extra money doesn' t mean that much. You wouldn' t change a decent boss for a bad one for a 5 or 10% raise, because a third of your life suddenly decreases in quality (and if you do, youÂ´ll regret it).
Also, on a less reflective mood, the phb seems pissy because the shots are on him for once.
This strip is different, as reflected in the nature of comments. Readers usually get a good laugh from Dilbert strips, but this one has gone beyond that, and has evoked some serious thinking and comments on "Employees prefer having a good boss...etc."
My view is that, as long as I get a decent salary that enables me to live respectably, getting a raise is much less important than having a good boss.