The office boy in Gemini studios was disappointed with his job because of his inability to be a star. This can be understood by analyzing the context and themes of the Gemini studios.

Gemini studios was a renowned film production company in the 1950s and 1960s in India. It was known for producing successful movies and launching the careers of many actors and actresses. The office boy, who was likely aspiring to be an actor himself, would have been surrounded by the glitz and glamour of the film industry on a daily basis.

The office boy's disappointment can be attributed to the following reasons:

1. Ambition and aspirations: The office boy might have had dreams of becoming a star in the film industry. Working in a prestigious production company like Gemini studios would have given him hope and an opportunity to make connections. However, as an office boy, he would have felt that his talents were not being recognized or utilized, leading to a sense of frustration and disappointment.

2. Observing others' success: Working in close proximity to actors, directors, and other film industry professionals, the office boy would have witnessed their rise to fame and success. This constant exposure to the glamorous lives of actors and actresses could have intensified his desire to be in their position.

3. Feeling undervalued: As an office boy, his role would have been limited to performing menial tasks and administrative duties. This lack of meaningful contribution to the film-making process might have made him feel insignificant and unimportant, further fueling his disappointment.

4. Comparison with colleagues: The office boy might have seen colleagues or acquaintances who started at a similar position but eventually managed to make a breakthrough in the industry. This could have intensified his disappointment, as he would have felt that he was not progressing or achieving his goals.

Overall, the office boy's disappointment in Gemini studios can be attributed to his unfulfilled aspirations and dreams of becoming a star in the film industry. The constant exposure to the glamorous world of movies, coupled with his limited role as an office boy, likely contributed to his feelings of disappointment and disillusionment.