Hardest thing to learn and accept is two different case, shouldnt put it in one thread

The point that TS mentioned about hard to accept bad thing happen to good people us just the matter of personal perception
Good things dun happen forever. When bad things happen, it is up to how people wan to deal with it, either with positive and strong or negative,blaming, whinning attitude.
The difficulty of accepting such things are totally subjective

Hardest things to learn?
Perhaps u are talking about unable to find out how universe are formed and how it will evolve after we are long-buried