What does it mean when a generally happy and ambitious person has lost all interest in existence?
It means they're depressed and should probably see a doctor.
Have you finally seen the real world?
Means person has found something else to occupy his mind.
ravenhill the blacksmith 1043A.D
it probably means this modern life has beaten them down.
they put their best face forward, but behind the scenes they are depressed and suicidal. that's really who they are. they need medical and psychological help.
It means that life doesn't come with a dancing clown that is supposed to make us happy all the time. Sometimes we are up and other times we are down.
Pat the cat