Why did they think Titanic was unsinkable?
You have to realize the time period in which Titanic was built. The gilded age was an era when new and wondrous things were happening every day. The Titanic’s shear size gave an impression of invulnerability. Most people don’t realize it, but the White Star line never actually claimed Titanic was unsinkable. This line was made popular by the press of the time, and maybe a few over-zealous shipyard workmen.