In the sense that no one feels anger for no reason. People get angry when they are either hurt or scared.
There are no bad people as well, however sometimes others' idea of good and bad doesn't match ours.
There is no problem that cannot be solved. There are problems that cannot be solved at the particular moment because of a lack of knowledge and possibilities. Often the only solution is to accept the impossibility of solving it.
If you lose an opportunity, it will always be followed by the next one, but in a different time and under different circumstances.