No, he did not realize it. He lived and died in the mistaken belief that the place he reached was the east coast of Asia. It was an Italian named Amerigo Vespucci who realised the mistake, and announced to the world two continents previously unknown to Eurasians and Africans. And that is why the two continents were named "America", after him.
Yara!
You are correct that Amerigo Vespucci was the explorer and cartographer who first demonstrated that Brazil and the West Indies did not represent Asia's eastern outskirts
However Columbus was not $tupid.
He fudged the numbers and names in order to get funding for his project. Back then it was rather impossible to convince people with money (the funders) that going West from Europe will result in finding new lands and new resources.
Columbus was smart enough to figure out the trade winds in Atlantic that loop in a way to take ships form Europe to Americas and bring them back.
this guy was years ahead of his time.
People with a bit of knowledge in his time knew that if you travel West, you will reach Japan.
So
please go beyond the newspaper reports.
Oh and "India" back then was not meant to be specific to modern day India.
It was a generic term used as a reference for all the areas Eastwards beyond Middle East and Africa.
And thus the terms India, Indo China, West or East Indies etc.
Back then most of the people now claiming to be true Indians in particular (and people of subcontinent in general) were busy in their own little world, supporting one raja over the other, till someone from outside would come rule their @rses. Sadly.
Good news is that many people from Indian Subcontinents became explorers and travelers during British rule. That trend continues till today.
peace
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