Speedrunners are built different, literally (lore [?] concept)
Start of the universe; when only the flames of Nether, oceans of the Overworld and the blank sky of the End exsisted.
Then in the End creatures we call "gods" now came into exsistance from nothingness, from black and purple. These cretures learnt to alter the universe with the thing they called 'code' of the universe, using it to create the rest of the universe as we know it now.
These "gods" had three major families, each reperesenting a dimension and modeling it as they wish and these families have many sub-families in it, each mastering a different way of the 'code'.
They no longer exsist now; they all died long ago, leaving nothing but remains of themselves in the End, things we call End cities and ships now.
Their bloodlines of the families also live on, even if they are no longer pure, in the veins of speedrunners. Because of this they urge to return to the thing they originate; to the void, to the nothingness. They try to reach the End, thier ancestor's homeland, as soon as they could and then free it from its protector.
But when they reach the End they are not satisfied as the End is no longer just the void, just nothingness. Things exsist in it. So the speedrunner, the player, tries it again. Restarting the cycle.
These people don't know all of this, they do it because it's their instict that they can't resist. It's something that calls them for the entirety of their lives.