What happened to the X-33 Venture Star? (video share of the month)

Yet another excellent video from Paul Shillito on the Curious Droid YouTube Channel.

I remember the X33 was all the rage when I was in High School & College. I forgot about it for quite some time.  I never knew what happened to it until I saw this video. It’s surprising that the linear aero-spike technology has not been used in all the new space craft that have been in development over the last few years.