Why do people ask "What is the purpose of life?"

This is a snippet of chat that happened between me and my friend.

me: have you ever debugged a program ?
friend: tell me
friend: lol
friend: joke ?
me: yes or no
friend: yes
me: and then after a long while you realized you are trying to debug a program/procedure whose purpose is something you do not know ?
friend: yes
me: and you do that and realize because you are "tracing" the stack to find where the problem is.. right ?
friend: whats the point u r trying to say ?
me: yes or no
friend: yes
me: well I just realized that when we are frustrated with life, and try to find[trace] where the fault lies, we are doing the same thing
me: and that is how many of us come to the question "what is life ? What is it's purpose?"