Why are niche ai companies popping up if the big ai company models were fed on so much data?

A user without an AI or tech background questions the emergence of niche AI companies, such as those for legal advice and emergency management. They recall that major AI companies like Anthropic and OpenAI fed their models with massive amounts of data. The user wonders why these specialized AI companies are appearing if large models like Claude and ChatGPT already possess the capabilities to provide advice on niche topics.