Columbus was convinced the world was a lot smaller than it is, and a lot smaller than pretty much everyone with more than 2 braincells said it was. So, since the world is small, and getting to India from Spain requires a long detour around Africa, with the hardest part going against the prevailing winds. He figured he’d just go west and get to India from the other side.

And, being the luckiest bastard in the entire Iberian peninsula, he didn’t end up lost in a giant ocean of nothing, but instead found land only slightly beyond where he calculated India to be.

Except of course it wasn’t. He’d go his entire life denying he was wrong though.