Or if you want to be more charitable, whatever opinion is most useful for the immediate moment. But I think that's an overestimation, lots of them aren't that coherent.
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.