Why many adults are not learning
Many people do not know about neuroplasticity, they think their brain and personality are fixed.
That is why they stop learning after the age of 20-25 years old.
They are not familiar with nature vs nurture.
Combine that with the straitjacket strategy of continuously telling people they are not good enough and you see that there is NO stimulation AT ALL to continue to learn, grow, change, and/or innovate.
It is a death sentence while being alive.