Answer:
For the fun of it.
Step-by-step explanation:
George Bernard Shaw's "Pygmalion" is a play that revolves around the life of a little girl named Eliza Doolittle who was 'hired' by a professor to teach her about life and make her into a duchess. The play deals with the themes of social class, education, and manners, etc among others.
This 'little' experiment that Professor Henry Higgins and Colonel Pickering was to take the flower-girl Eliza and make her into a duchess, thus, promising to make her a lady. Act V is when Eliza had run away from the duo and was brought back to decide who "owns" her. Higgins asks her to return to him, which prompts Eliza to question why she should come back for. Higgins replied, "for the fun of it".