This is a good question. Erik Larson's book The Devil in the White City is the story of the Chicago World's Fair in 1893. It traces the creation and building of the World's Fair as well as the actions of a serial killer who capitalizes on the crowds and confusion of the worldwide event. Understanding the symbol of the Titanic is the first step to answering this question.
The Titanic was known as the "jewel of the ocean," and it was grander and more opulent--as well as faster--than any other ocean liner ever built. It became the symbol of the most advanced technologies and extravagances to be had anywhere in the world. What happens on the Titanic's maiden voyage has been well documented: it strikes an iceberg (mostly through human error) and it sinks, taking hundreds of people with it because no one was prepared for such an occurrence. The Titanic has become a broader symbol of a grand thing which fails due to pride and human error.
Given that, the use of the Titanic in this story is a perfect foreshadowing of what is to come. This particular World's Fair was a celebration the four-hundredth anniversary of Christopher Columbus discovering America and the ingenuity and accomplishments of the country since then. The hope is that it, like the Titanic in Europe, will be the grandest, most opulent display of American culture. The parallel is clear.
While it is true that there are enormous challenges and obstacles while building the Fair, it is completed and it is a glorious spectacle--just like the Titanic. The elements of human pride and arrogance also show themselves in the building of the Fair. The exposition itself does not fail; however, the presence of a serial killer who stalks his prey virtually in the shadow of the Fair is certainly a horrific disaster.
The sinking aspect of the Titanic is less applicable to this story than the glorious creation of something to display ingenuity and imagination in ways which had never before been seen. Both the Titanic and the 1893 World's Fair in Chicago do that.