ML these days have moved forward fast that books are outdated after couple years. Look at articles, podcasts, youtube videos, and research papers for the latest changes. ChatGPT utilizes existing algorithms. Its insight is scaling the weight parameters up to billions, and human feedback & guidance help a lot in finetuning the model to be user friendly to general users.

To understand LLM from ground up, the following topics would help.

  - Machine Learning basics. e.g. weight parameters being trained.  
  - Neural Net basics.  
  - Nature Language Processing basics.
  - Word vectorization, word embedding. e.g. Word2Vec.
  - Recurrent Neural Net basics.
  - LSTM model.
  - Attention and Transformer model.
  - Generative model like GAN.
  - Generative Pre-trained Transformer.

I might miss a few topics. Actually ask ChatGPT to explain each topic. See how far it goes.