This paper explores the adoption and use of AI chatbots by knowledge workers in the Italian legal sector. Distancing ourselves from existing literature, which mainly examines chatbots as interactive agents and focuses on the implications for human agency, this paper concentrates on chatbots as tools for text manipulation that knowledge workers use. We collected data from 39 respondents to explore the causal factors influencing the usage behaviour of knowledge workers. The results of a fuzzy set qualitative comparative analysis reveal four causal configurations identifying four profiles of knowledge workers: enthusiastic explorers of the technology with a positive attitude towards innovation on one side, and cautious collaborators, team-oriented innovators, and intensive independent users who approach AI chatbot usage more critically, whether in individual or teamwork settings. Our research has implications for both research and practice, highlighting the need to advance the investigation into the lack of perceived risk associated with AI chatbots and examining the role of usage intensity.