But its not abnormal. Last election, it was basically half the country.

No, it was a third of the country. Regardless, we're not talking normality in the sense of what's average or prevalent, but rather deviation from the normal, healthy operation of the human mind. That whole third of the US population seems to be suffering the psychological symptoms of lead poisoning, for instance, and that's abnormal.

Right now their worldview is completely in flux because they shape their opinions around whatever Trump is doing that week.

Wrong again. They shape their opinions around whatever helps them maintain control, impose rationality, and avoid consequences. They follow Trump because they see in him a fast track to a society that caters to this mindset.

But its getting legitimately hard for them keep up and Trump is loosing support online and in polls (55 to 23-33%) because of that.

Because he is seeming less and less to them like the guy who will be their fast track to a society that caters to their mindset. The personal cost to them for pursuing this course is growing beyond the point where their perceived reward is worthwhile.