Why must there be a NEED? Why did we ever send ships across the ocean to explore? Where was the need? People like doing science, and so we're doing science.
That was (for the western hemisphere) mostly to steal gold and silver from other civilizations. Oh, and to grow addictive drugs for export, like in Virginia. It was never done for other than banal reasons, although I'm sure pious rationalizations were offered to make people feel better about the ongoing genocides.
That feels like a bit of rewriting the past. How could someone plan on stealing valuables from somewhere across the ocean... before they know there even is an "across the ocean" to get to?
It also feels quite off to reduce all of human curiosity to a means of getting one over on someone.
That wasn't the motivation for the first trip, but it was for continuing it all. It was driven by economics, as anything large scale must inevitably be.