This is rather an intriguing comment, isn't it? One way we can start to try and work out its significance is by looking at it in context and seeing whether this sheds any light as to its importance and significance. If we look at the flashback carefully it is when Victor and Thomas as children are rushing to watch the festivities to celebrate the 4th July. When they finally arrive, what they see seems hardly worth the effort of attending:

The fireworks were small, hardly more than a few bottle rockets and a fountain. But it was enough for two Indian boys. Years later, they would need much more.

Taken in this context, this remark can perhaps be seen as applying to the way in which their hopes and expectations would be much greater when they grew up. They would not be so easily satisfied with such a pitiful display of excitement and wonder. The quote therefore relates to the way that as these characters grow and develop they would have greater expectations of life and of the kind of excitement and sense of wonder that it would contain.