If they hadn't happened across the Americas, they would all have died. India was nowhere near where he thought it was, and almost exactly where the common knowledge of the time (and Eratosthenes) said it was.

Sorry. It's just a pet peeve of mine when people think Columbus was somehow right, or even worse, that people believed the world was flat pre-Columbus.

EDIT: To be clear, I'm not implying you think that, but it seems to be implied in the Sagan quote that Columbus was something other than completely wrong in his assessment of the situation (or possibly lying 'cause he wanted to explore the other side of the world. He certainly seems to have been brave enough)