The Long Term Capital fiasco in 1998 was a hedge fund that went bust and almost took the world financial system with it.
As a result of the LTCM crises, the federal reserve pumped money into the markets which resulted in the 2000 stock market bubble.
That could have been a factor, but there was a lot more going on than that.
The constant bellyaching from Greenspan about his dislike for the stock market and all the wealth it generated actually encouraged speculative behavior. Why would any one want to invest for slow long term gains when it was apparent that Greenspan was going to take a wrecking ball to the whole thing in the near future?