a) "I believe the distance is smaller and that we'll be able to get there no problem (as much as a trip like that could be ""no problem"")"

b) "distance is bigger but there might be something in between, etc, and I like adventures"

c) "distance is (or might be) bigger and this will be a very boring trip but we'll eventually get there but might have to wing it.

Ptolemy estimated that the continents of Europe and Asia collectively spanned 180 lines of longitude, leaving 180 to travel by sea. Most contemporary scholars believed this too. In actuality, the continents span about 130 from China to Spain, leaving 230 that would need to be travelled by sea. The best sources available to Columbus were wrong, and the other available sources typically erred on the ocean being too small. Few, if any, people thought Europe and Asia spanned less lines of longitude than estimated by Ptolemy.

Additionally, he read that each line of longitude spanned 56 2/3 miles at the equator. Unfortunately, his source was quoting Arabic miles, but Columbus was only familiar with Roman miles, which are shorter.

He didn't believe that he discovered something the scholars of the day didn't. The fragmentation of the Mongol Empire meant that overland trade was growing more expensive, meanwhile nautical technology and seamanship was rapidly advancing. It would have been impossible to have made Columbus' planned (as he understood it) sea voyage in, say 1300. But now, the overland route wasn't well run, and the caravels used by Columbus were much better suited to ocean travel.

If Columbus hadn't done it, the economic necessity of the rising price of goods and dropping costs of sea travel would have resulted in someone else doing the same thing. Some people say he was a unique visionary, other people say he was dumb and lucky. Neither were true. He did his research and came to the natural (if wrong) conclusion. (he was lucky though)

https://en.wikipedia.org/wiki/Christopher_Columbus#Geographi...

The fall of Constantinople and the the Ottoman Empire Also made trade routes more expensive

There were also efforts to circumnavigate Africa for this reason

And yes if it wasn't him it would have been someone else.

Going west from Europe to India doesn't make sense today, it seems the Cape of "Good Hope" was reached (but not crossed) before Columbus's voyage.

It's getting back which is the issue - your have the disastrously weathered cape of good hope, or the pirate-infested Aden. It's quite ironic that if you want to sail around the world, it's the ancient routes that are the worst parts.

If Columbus had discovered the Americans were an archipelago, or if the gulf of mexico had properly separated north and south, the discovery would have been a very popular trade route - even today.