My boyfriend’s friend wanted to let me know that I shouldn’t use chatgpt. He promised to explain why but never did. Why is it so bad?

I let him know that I only use it to learn. I compared what the chat said with my own knowledge. I try to keep it to the bare minimum. I was particularly interested in the explanations the chat provided and I found it to be very interesting. I want to learn more and read more but I’m currently busy with work and other stuff. I want to use this time to think more about how to improve myself and learn more. I take that the chat isn’t very trustworthy, so I promised I wouldn’t use it to do anything. I compared what the chat gave me as a result to what I already know.