> Someone could have built the Rift in mid-to-late 2007 for a few thousand dollars, and they could have built it in mid-2008 for about $500.

That's not true. The thing that enabled the Rift was the rapid improvement in cell phone screens in the early 2010s. I know because in 2011 I was trying to design a VR headset that was basically the Rift. Readily available screens at that stage were nearly, but not quite, good enough (most were around 720x480 iirc). I spent ages playing around with lens and mirror setups and fixed foveated rendering etc. and came to the conclusion that it wasn't doable (yet).

My failure of imagination was not realising that, while screens in 2011 were inadequate, they were improving in resolution and response time rapidly and were about to cross the threshold from useless to useful.

A year later 1080p screens were the norm and the Rift was a reality, but in 2007 it was a pipe dream.

I love everything written by Gwern. One day I want to meet him if he lets me.

But I am not sure I agree with this one. At least in my personal experience, I had several good guesses at where tech was going since about the late 90's, but couldn't capitalize much on it until very recently (e.g. by investing with my micro-VC fund).

Perhaps it's my experience that's skewed, or perhaps I think too highly of my past intuitions.

Oh, I thought it would be about timing instruments, crystal oscillators and such, maybe time transfer protocols...

"Hindsight is 20/20."

Said someone better than me.

Elliot waves and quantum entanglement.