Obviously Alexander did not conquer even the world known to the Greeks:
1) He never went west so he didn't conquer anything in Italy, nor bother the Gauls or Germans or Iberians. All were known to and traded with by all of the "Greek" world.
2) He took Egypt but not any of the nations that routinely plagued the Egyptians from the south. All were known to and traded with by the Greeks at least as far as Ethiopia.
3) He didn't take India. If you want to argue it was not known to the Greeks, it was only its detail that was not known to them, not its existence and what they traded for that originated there. They were also fully aware of the trade along Persia's coastline into India (Alexander returned from India via this route and it was planned, not opportunistic) and the monsoon trade routes.
4) He knew dimly of China as there was already a full trade chain linking them to Europe though it was in its early stages (trading place to place along the way, not caravans travelling the whole distance, nor the full-fledged monsoon trade through India that bankrupted and brought down the Roman Empire).
He failed in India NOT because his army revolted. His army revolted because India was an entirely different prospect than Persia. Persia was a huge feudal empire with an emperor nominally in control but really more of a cat herder. If they would (not could, would) have ever brought their full force to bear on Alexander, they'd've crushed him. Of course, they couldn't and he knew that. When he beat them a couple times, those opposed to seeing him as overlord were largely dead. Many of the rest didn't see any particular reason to acknowledge him either.
Which is why he never conquered a large portion of the Persian Empire. Only those places he took an army too or whose forces had fallen against him and so had no armed defense against small garrison detachments. But a large part never gave in, but rather were happy to have no overlord at all. Alexander could have pacified the empire, much like William the Conqueror in England, but it would have taken a lifetime and every time he turned his back... This was not for him. Too... mundane... apparently. He seemed awesome, but really it was a matter of getting a surrender before the governing means was shattered completely.
Had that happened first, Persia would then have been like India. Lots of piddling little cities and power centers, none of which would have been tough to take on its own, but sooooo many of them all needing taken one by one by one. No lovely "all fall down" effect like he got.
So. India. Not "India" in that there were no overarching empires at that time. Just a million (OK, perhaps 1-2,000+) little polities and that just in the north where the most wealth was at that time. Alexander would have had to take it city by city and before long would have had an army of Indians, not Greeks, just due to wastage of his men. After five lifetimes, he might've churned his way through northern India. The amount of work was just too massive for the size army he had.
And his attention span. You buy that you are a god amongst men and it's hard to slog about taking one city of 3,000 people a week. Grunt work. Not for him at all.
And he never could have even reached China, not likely even as a single man visiting. He certainly had no way to take an army there.
So people go on as people do. "Conquered the known world" and such. We all do that, we all like that. Shows how idiotic we are setting up a falsehood and then defending it with our intellectual lives. Moronic as American blacks going on about Egyptians being black in the same manner. We all need to be proud of what we all actually do have as achievements in our pasts. They are all impressive enough. We don't need to make up false ones and then lose sight of the real ones defending the undefendable.
I, for instance, do not need America to have been perfect in every modern way, decent in every modern way, and blameless in all things past, present, and future, wonderful in all ways. (That still doesn't mean the idiot Canadians who say THEY somehow won the War of 1812 get a tolerant smile and nod.) But I do take pride in the things, magnificent and small, that we actually HAVE accomplished, and will. All should do the same.
Alexander won a few big battles, won a lot of small ones, failed to do much after Persia, and I can honor him for what he did accomplish without claiming he was more than he was.