in my views ,  no matter money , time , friendship , family ... put them together , one word : interest

when you are in the interest field , your own emotion is coming , then , you want to do something to keep it safe or more, it's very terrible experience, all your thinking , your strong , your destination will be broken .

take a simple ,  when you are parents , you will put all your attention to your child , if your child is going to get some hurt , you will be nervous , fear

and want to do something to change this situation , but ...

this is the very considering by yourself , as we know , our brain is limited , we can't put everything in it , this is the  common ,   but I think , the brain is used to spread 2 part ,  one is the emotion , it's from the gene , and through 1000,000,000 years  ,  at that time , it brings a very hug interest to us, but , time is change , in this time , we need to not only the eat, live , wear , walk .  

other part is the wisdom ,  what a pity , wisdom is very slowly , and small ,  why , because in that far time , even if we don't have the wisdom , I can also live , yes , maybe I find a way out , if you don't care your life , if you consider your death as home , maybe everything gone be alright , but that's also a pity , I can't do this ,  I have a very long road to go