Both. The story of credit is the story of triggering greed, losing common sense, etc. It's the difference between investing your own money for the long term and playing with someone else's money for short term gains.
The Nasdaq crash was driven by bad investment from the VC side and stock deals where companies were buying companies left and right by printing their own money. One of my partners would wander by my office telling me that NORTEL or Lucent had bought another company for $3-4 billion in stock and no one would bat an eye goven how common the practice.
Also, you cannot ignore the mandate that telcos had to share their netwoks with competitors at sub market prices which gave rise to a whole bunch of pretenders that were never going to be able to be cash flow positive as well as their suppliers, and the lies that said Internet traffic was doubling every 9 months. Oh, and let’s also not forget the inability for companies to truly value E-business models. That was a whole other story....