The Fall and Rise of Reginald Perrin (1976)

Disillusioned after a long career at Sunshine Desserts, Reginald Iolanthe Perrin endures a midlife crisis and fakes his own death. Returning in disguise after various attempts at finding a 'new life', Perrin gets his old job back and finds nothing has changed. He is eventually found out, and later finds success with a chain of junk shops. However, it becomes so successful that he feels he has created a monster and decides to destroy it.