People assume children have high neuroplasticity because they are young, but what if this is simply a correlation incorrectly assumed to be causation?
Neuroplasticity increases in response to learning lots of new things. Like the first week of school when you come back from summer break, learning is hard, almost painful. It takes the brain some time to increase it's neuroplasticity and adapt to the learning environment. Children are simply this way because EVERYTHING IS NEW TO THEM, and that's the only reason why, I would assume. Children haven no choice in this. It's simply a fact of life that everything is new for them, and the novelty of their life experiences triggers more neuroplasticity.
Older people have less neuroplasticity because they have "learned" to be creatures of habit. It's easy, almost lazy to do the same thing day in and day out. The rote repetition of the same activities day after day decreases their neuroplasticity, thus making change more difficult or painful. (painful as in 1st day back from summer break painful) This "pain" (still don't know better word to call it) encourages them to not change and continue doing the same thing every day, and reinforces their behavior.
That's my understanding of it anyway. Maybe there is some minor age related factors at play, but saying old people can't learn is like saying old people can't exercise or work out. It's very literally the same thing.
