Partly because analysts are learning their lesson in underestimating the AI demand and starting to correct for it.

The other complication is that we don't have intuitions for AI, so it's easy to underestimate how astronomically large the market will be.

And from an execution standpoint, Jensen (Nvidua CEO) has been preparing for a very long time (albeit unintentially, so nobody could predict AI to this extent). He also tends to go all-in on things, which has caused problems in the past (e.g. crypto crash), but just happened to be incredibly prescient in this moment.