Perhaps a False Expectation

I was reading in Luke 2 this morning, and the thing that struck me was that Mary and Joseph, although they had been visited by the angel Gabriel, had seen the miraculous, immaculate birth of Jesus, still found themselves surprise and confused by comments of Jesus' future.
Ex: 8 days after Jesus' birth, as was the Jewish custom, Mary and Joseph went to have Jesus circumcised. Simeon, a just and devout man, waited for the Messiah to come one day and when he saw Jesus coming in the arms of His parents, he spoke of Jesus' purpose on earth. The bible says that Mary and Joseph marvelled at the things that Simeon said. Later on in this chapter, Jesus is left behind in Jerusalem by accident. His parents thought He was with other members of the family but once they returned to Jerusalem and found Him teaching elders about the bible, they were puzzled and asked Jesus why He did this to them. He asked them why were they looking for Him? Didn't they know He had to be doing His Father's business? Again, they were struck with confusion.
I can't help but wonder if they misunderstood God's message to them that came from Gabriel.
During this time, there were no Jewish king as there had been many years ago, (Old Testament) and they were oppressed by the Roman King. Life for the Jewish people was lived in fear and oppression. They hoped for a Jewish king to rule them and some misunderstood Jesus to be that future earthly king. I wonder if His mom and "step" dad thought that too, so when they heard He would be the Saviour of the world, and doing "His" Father's business, which Joseph was a carpenter, not a priest or scribe, this would confuse them.
How does this apply to us, to me? I think the main reason we get disappointed with life, is because we have a false expectation of God's purpose for our life. We would like to see things in a different way, for life to treat us in a different way and have more of what we want. Sometimes, we see that we are living the way we should but life seems purposeless. Sometimes, although we are saved and doing the best we can, we're still unhappy. A false expectation...
I know that God has a plan for each individual person on this earth. First, is that all shall come to repentance (2 Peter 3:9) second, that we should take up our cross and follow Him (Matthew 16:24; Mark 8:34; Mark 10:21; Luke 9:23) and that we should tell others about Salvation through faith in Jesus the Christ (Matt 28:19-20; Mark 16:15,16; Luke 24:27 etc). Those three things give us freedom, peace, hope, joy, purpose and direction in life; what else would a person want? If we are unhappy, I believe it's because we have a false expectation of our life here on earth. Just like Mary and Joseph had a false expectation of Jesus' future.