Why did the Titanic hit the iceberg?

According to my knowledge about this, the iceberg that was crashed appeared small so the captain decided to crash it. Unfortunately,the size was super massive beneath the water. Titanic was claimed the most gigantic cruise that can't be sink or break.
From what I saw on National Geographic channel about Titanic, the incident had conspiracy while making the ship. But I don't know if those were true or not.

These are some of my own opinion.

- I think the boy on the deck that suppose to survey the path can't focused while watching from the top because it was so cold. He should observe the iceberg carefully and Titanic wouldn't have to split. Well, he should know more about the sea as it is his job.

- The people who were involve in making this huge ship were not smart enough. Maybe it is because of the technology around that civilization. It was not good enough. Maybe some of the theories were wrong. So this substances that were used were low quality items.