I would say that we "lose" that playful ability for reason. As we age and have more responsibilities, time spent doing things that have "no benefit, no reward,

I would say that we "lose" that playful ability for reason. As we age and have more responsibilities, time spent doing things that have "no benefit, no reward, no ultimate reasoning" means time not spent fulfilling other responsibilities. One may argue that playfulness fosters creativity that eventually helps us fulfill other responsibilities better (e.g. create a more innovative startup, be a more playful parent). This is the classic trade off between exploration and exploitation. We tend to explore early on, then exploit the gained knowledge later.