Explanation: It was a common pop history misconception in the 20th century that Columbus believed the world was round while everyone else was a flat earther, which is why he attempted the expedition to Asia.
... the truth is that everyone who wasn't an utter fanatic or backwards peasant (which, tbf, were both non-negligible portions of the population at the time) knew the earth was fucking round. Since the Classical era, for that matter, academics had engaged in scientific experiments to demonstrate the approximate size of the earth, even. The reason why Columbus was jonesing to sail, and no one else did before him, was because everyone else knew that Asia was too far to be reached by extant ships, with everyone onboard doomed to die a horrific and slow death of dehydration and/or starvation before reaching Asian shores.
Columbus, on the other hand, believed his (INCREDIBLY faulty) estimations of the earth's circumference were correct, and everyone else was wrong, which is why he was so ready to make the trip. Spain's monarchs, looking for a new advantage, took a gamble with a (relatively) low cost, gave Columbus a few ships, and said "Godspeed you, brave idiot, and hopefully bring back trade routes for the prosperity of the Crown"
Columbus lucked the fuck out by finding an entire continent lodged between Asia and Europe (he still believed he found Asia even on his deathbed, even as everyone else started saying "Wait, shit, Columbus didn't find Asia, he found something NEW"), otherwise, his expedition would've ended with nothing but three ghost hulks led by an eternally cocksure idiot.