Tonus- Getting rewarded afterwards still doesn't negate his realization that his life could be upended at any moment, no matter how devoted he was to serving god. This is the nature of Jehovah, a being whose nature is unchanging. This is god, forever.
It would seem that it isn't about our own 'complete' satisfaction in our personal life then. You may not feel the same as Job did at the end of this passage, which was "repentant" and "full of years". Repentant because he, the creation, questioned the Creator. The book itself acknowledges that God is ultimately behind job's affliction.
The book confirms that we have as much, or as little, depending on what God sees fit. This message is clear throughout the entire Bible.
Man expects much because he considers himself deserving. But neither of these things are clearly (by biblical accounts and our very own personal experiences) up to us to decide.