>Is AGI really achievable?

It does appear to be well within the possibility space under physics. There is no way to really know until someone creates a working example. The current products of deep learning don't appear to be capable of truly understanding the material in its training corpus and is instead simply learning to make statistical connections that can be individually unreliable.

The training corpus contains both fantasies and reality; there is no guarantee the most popular connections aren't delusional nonsense from twitter or FB.