The Jewish People in Egypt were steeped in idol worship. The ultimate idol is man himself. Pharaoh declared himself a god. Hard work can bring a person to appreciation of G-d's beneficence. I did all this.
Hard work can bring a person to a sense of self-esteem.
Or it can fill him with self-importance. Hard work never killed anybody but it can turn us into addicts. It can make us think we are the center of the universe. The ultimate definition of a workaholic is someone who has confused what he does with who he is. The New Moon too is a call to renew our relationship with G-d, lest we become trapped in spiritual stagnation.