Usually cos of dementia, brain deterioration and lack of education.Plenty of older people are quite dumb and immature.
thors the son of a king. he aint denied an education. given his life expectancy is 5000 years he shouldnt be experiencing natural brain decline. However, his brain may be deteriorating due to all the hits to the head. Possibly from failing to catch his own hammer.
so i guess im wrong. There is a rational reason. i stand corrected.