It's some combination of those things. Lots of them are just random filler and arbitrary ramblings, but the ones he gets pressed on repeatedly are answered in whatever way provokes a desired reaction at that exact moment. Some of it even seems to be remorseless and haphazard A/B testing. He's well beyond a severe pathological liar, as most such people would lack an innate desire to deceive with such intense frequency, and there might not even be a name yet for whatever trait he exhibits. Psychologists are just forbidden by their licensing body from commenting on a president's mental state while still in office.